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Laptop screen blanks out TV screen at login

Hello all,

I have a friend whose laptop runs health info messages on a TV screen in the lobby of her office.  They create the info in the laptop.  The laptop does not run the info on the TV screen, though, and is taken back to the setup room it normally occupies. The TV runs the info.

Now, the TV will see the bootup of XP through to the login screen, at which point it goes blank while still showing it is in PC mode in the upper right corner of the screen.  In the meantime, at the login screen, the laptop screen takes over the duties of video.

This is pretty much beyond me. I volunteered to check on it thinking the FN key was toggled, but it is not.  Since the TV goes blank at the login, I figured XP was stopping input to the TV screen at this point, so I disable the Firewall and removed the login password to check, but neither of those were causes.  This combination worked last week when they changed the messages on the TV screen successfully.  Any Ideas as to where to check next?  Would drivers just have quit working like that?  I ran Ccleaner, Ncleaner, Malwarebytes, and found the Dell Vostro to be pretty clean.  There were a number of Registry problems, all minor.  Didn't run Combofix or Sypbot.  

Thanks
royalm
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Michael DyerSenior Systems Support Analyst
BRONZE EXPERT

Commented:
You might login to the laptop and then check the display properities.  Right click anywhere on the blank desktop and select properities.  Then, go to settings and look at how it is set - it should be set to multiple monitors for the video to show on the TV.  

Author

Commented:
Thanks for the idea Equitrac_Michael, I will give it a check in the morning as soon as I can.  I can Crossloop to it to check.

royalm
Um, well, seems to me there are four "modes" a laptop's built-in video can typically do, either 1) only the internal screen, or 2) only the external video, or 3) extend desktop where the internal monitor would show the logon screen and then the external would have "extended desktop", or 4) mirror where the external and built-in display are same image.

So, to have something on the TV with something else at the laptop sounds like 3).  I infer this since you seem to suggest one thing gets displayed on the TV while something else is on the laptop screen.

There is usually a Fn-key combination that toggles through these.

However, there is also another "twist" in all this.  Old laptops usually had a VGA connector for external monitor and perhaps an SVideo plug of the old video casette recorder type for older TVs.  Newer laptops may have a VGA connector as well as an HDMI port for connecting to new-style digital televisions.  I would say the vast majority of laptops CANNOT do the external VGA and the extral HDMI, it is usally either one or the other.  Where the problem may be, usually at power-on-self-test boot-time the external VGA monitor may work, so what is happening is the video card is "assuming" it is the VGA connector that it should feed the external signal to, only after it gets far-enough along in the detection or user-settings does it "know" that it should send picture to the HDMI instead.  Ideally a good video card driver will detect if a TV/display is connected to the HDMI, and if so, then should "think" that it is the HDMI to send the external picture to not the VGA, but, it might be that your video card driver that comes with this laptop makes the choices for which displays to display on a user-by-user basis, such that, when you are at the user-logon screen, it has yet to decide which user preferences to go by.

For many graphics card drivers, under Windows, right-click Display, Properties (or Control Panel, Display) you can specify whether the laptop's internal screen should be screen "1" and the external "2" or vice-versa, and for desktops it's more common and even some BIOSes let you specify whether the built-in motherboard video or the AGP or PCI video card should "take precedence" and therefore default as "1", BUT be aware for some laptops this is not possible.

Sometimes if two displays (internal and external connected) are both detected as present, some applications like Windows Media Player or PowerPoint slideshow will show the video/slideshow on the external "extended" desktop screen by default.

In any case, once the user is logged-in then it should be possible to Fn-key combination or Display properties to get the external HDMI connected or VGA connected TV to display the extended desktop so that the application that runs either positions it's window to the second monitor, which is the tv.  So it may be the customer must log-in at least, and maybe even choose some settings, for the laptop to properly display to the TV.
It could also be that sometimes the laptop is sending picture to the HDMI but the screen resolution does not match what the television is capable of displaying, so the television is showing black because of that, and as soon as you change it so the extended desktop resolution matches the TV set's capabilities, then the picture shows.

Depending on the capabilities of the television, and the native resolution of the laptop's display, some TVs cannot display "mirror mode" because the laptop is in a 768 lines of resolution that the TV does not do, change to "extended" and then the TV can do the 720 or 1080 while the laptop is 768.

Author

Commented:
Thanks ocanada_techguy, I will be onsite there later today since she can't seem to get into Crossloop for me this morning and can't follow directions well.  I will check out the dpi (?) in addition to the multiple monitor settings.

royalm
sure.
To your point about "it used to be okay why is there a problem now?" question, maybe they changed screen resolution, or
maybe windows automatic updates updated something that has adversely affected the display driver, BUT really that is unlikely, because normally the only updates that are automatic are the critical and recommended ones and usually hardware updates require the user proactively choose them, but maybe somebody did.  Still, you can check windows updates to see the installation history to see if somebody updated some optional hardware drivers that way.  Unfortunately "drivers" are a bit different from WU updates, a few driver updates are WHCL compatible and are in the "hardware" category of Windows Update, but some drivers from the manufacturer are more complex and not part of WindowsUpdate.  For those cases, you could look at system restore points calendar without doing actual restore, many will be notice if any of the bold dates show that a restore point was made because "such and such" was installed.  Luckily even if driver updates are not in the windowsupdate history, and even if they don't appear in the calendar of system restorepoints, it is possible to "rollback" a driver to a previous version.  In device manager, on an individual item properties, driver tab, there is a rollback button.  However your problem is, without some kind of reliable history or recollection on the part of the administrator of the machine, you have no idea which one(s) to roll back.  The question is always "what recently was changed?" so you can "undo" it, but if the users of the machine cannot tell you, that's a problem.
If you had just tried updating some display drivers and then the problem happened within a few days or weeks, you would know "oh, I need to undo that", or like when internet explorer starts blowing-up or you start getting blue screens, they always say "if you recently added and add-in or changed some driver or software, try uninstalling it or reverting it"
I'm sure I'm not telling you anything you don't already know, since you quite rightly ask if anyone knows of something along these lines that would cause the behaviour described.
And, it is very slim chance but it is not out of the realm of possibility that a critical update to some other part of Windows is now causing a new issue with the display.  Since you mention remote assistance type software, that kind of software could be the culprit, causing a "change in behaviour" to the way the display properties are handled, so, could it be remote control software was installed around the time the change in behaviour started?  More than just uninstall, you could use System Restore to "undo" put the system back the way it was before it was a problem, assuming system restore still has restore points back that far.  But then you'd have to repeat all your anti-malware detections.  

Best course of action is likely first to see if as things are you can figure out if there is a way "going forward" to get it working.  Because the most likely solution is going to be to adjust the way the user uses it, what steps or what settings the user must now follow to make it work properly, which could be as simple as a few extra mouse clicks or key combination and the correct choice of screen settings to fit the circumstances.
Maybe there are broken pins on the cable, as would happen on sVideo and VGA plugs constantly being plugged and unplugged.  Let's hope it's not the case that the external display port on the laptop itself went defective, burned-out, broke connections inside, or was shorted-out, or for some reason is now broken.

Author

Commented:
Hello ocanada_techguy,

I didn't have the opportunity to work on this for the last 3 days because her office was closed.  I just got hold of them to make time to connect and will get to it shortly.  The pins were the first thing I looked at - possibly to make a short fix with a new cable, but the new cable didn't fix the problem.

When XP boots it is on the TV, then when it comes to the login and password, the TV quits and the laptop screen takes over.  The Fn key doesn't work at this point.  That's why I thought maybe some corrupted or missing login files coule be causing the TV to stop playing allowing the laptop to take over.

I will return after a while to let you know what I have found regarding the ideas from above.

Thanks
royalm

Author

Commented:
Hello all,

I have reconfigured the laptop from single-laptop to multiple screens, and it is just like before.  The only difference is when the TV gets to the login screen, and the laptop takes over the screen at that point, the TV screen is the default blue desktop background color now with nothing else but the "PC" in the top right corner as always.  But the screen is not the dark gray/black it was before.

So the TV still cuts of at the login screen, but now has the default blue of the laptop desktop only, no icons or taskbar, and the laptop takes over the screen duties.

Does this narrow down the ideas any?  I want to go to her office and make sure that SP3 is installed ( believe it is), all updates are downloaded, and to see if there are any updates to that particular video driver. I have already gone through the gamut of maintenance programs and know that the laptop is clean (I guess that doesn't mean that files are'nt missing or corrupted).  I just can't see a hardware problem causing this interference between the laptop and the TV at the login only.

Any other ideas?
Thanks
royalm
Michael DyerSenior Systems Support Analyst
BRONZE EXPERT

Commented:
It sounds like it may be extending the desktop on to the second display.  Right click on the desktop and check the properities to see if there is a checkbox on the setting, "Extend my Windows desktop onto this monitor".  Uncheck this and see if that puts the display on the TV Screen.

Author

Commented:
Thanks Equitrac, I'll give that a look when I can Crossloop with them today.  

royalm
Commented:
Hi all,

I havea done all of the above possibilities, and still can't seem to get the TV screen to stay on past the login screen, at which time the laptop screen takes over.  We have found that the other laptop they have does do the job correctly, though.  I will see what settings are the same or different since both laptops are Dells.  Until now, I did not know that the 2nd laptop could be used for the same program.

At this point, the best I can do is check settings and let you all know what the answer will be.  But it will be a few days more until I can get to both laptops at the same time.

Thanks for all the input and ideas from everyone, and I sure wish one of the tries would have worked.
royalm

Author

Commented:
Since none of the tips and ideas provided an answer, I will try to compare laptops and see what differences there are.  I can then post what I have found.

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