Windows XP COM Port Conflict Error 633

Posted on 2004-11-09
Last Modified: 2013-12-27
I have been working on this issue for over a week now.  I have searched the net until my eyes glazed over.  I finally decided to cough up the cash to give this ago.  Unfortunately, it appears that while this topic has been addressed a number of times, there is no silver bullet.  Nonetheless, I paid for a month, so here we go.

I purchased a Dell Dimension 2400 for my brother-in-law's family as a Christmas gift last year.  About a week ago, his modem stopped working.  A few days later a buddy of mine called me asking for advice about his "top of the line" Dell as well (a year old).  His modem stopped working as well (COM Port Conflict, Modem in use, etc.).  I have only had a chance to tear into my brother-in-law's machine.  It has a Conexant/Asus SmartHSFi V92 56K PCI Modem.  I am unsure of the Motherboard model, if you can point me to a nice freeware utility that would allow me to look it up, I will get that information for you as well.  If I try to query the modem in the diagnostics tab for the device manager I get the same "COM Port not available.  There may be a hardware conflict..." message.

Here are the things I have tried (over and over again in various orders):

1) Changed around the COM ports the modem was using
2) Uninstalled and reinstalled modem
3) Uninstalled and reinstalled modem and COM ports
4) Switched the Modem around in different PCI slots reinstalling the modem each time.
5) Bought a brand new modem, installed it.  Continued to receive the same error messages.
6) "Rolled back the system, drivers, etc."
7) Ran a Windows Repair on the system with the Windows Install CD
8) Updated all drivers
9) Experimented with various drivers
10) Updated the BIOS to most recent version (i.e. "A05")
11) Ran all of the Windows Update functions through Win XP SP2 and then installed the modem
12) Used CTRL-ALT-DEL to terminate every possible program to determine if some software had obtained access to the COM port
13) Finally did the ultimate.  Booted form the installation CD, deleted the system partition, created a new system partition so as to format the whole thing and wipe everything clean.  Installed a fresh copy of Win XP with absolutely no other software installed.  Installed the modem with the drivers that came with the computer when it was shipped one year ago (and worked).
14) Repeated step 13, but this time installed the brand new modem.    Same @#%#@!% error!!!!!

This is killing me!  The only thing left that I can think of, is replace the motherboard ... unless you can help.

And, call me suspicious, but it seems very fishy to me to be running into this error on not one, but two PCs at relatively the same time frame and both are Dell machines.  Furthermore, it seems as though Microsoft sure has a fair number of knowledge base articles on this topic making me wonder if there really is something other than a motherboard issue here.  Anyway, all conspiracy theories aside, can any of you provide me something that would allow me to put this behind me?

Thank you!
Question by:dsoethout
    LVL 31

    Expert Comment

    Many internal modems are software modems. They typically work on COM 3 - COM 5 and are entirely dependent on drivers and the O/S to function at all. These modems are not necessarily bad, but they are more susceptible to failure/problems because they are:
    1) Cheap, in a wide sense
    2) They can be compromised by BOTH hardware and software problems.

    It is not entirely impossible that two modems die within a small time window.

    A more reliable, but somewhat more expensive, solution is to get an external, proper modem. These rarely give you grief, unless they're hit by lightning or suffer some other electrical or physical abuse.

    Author Comment

    Got one you would recommend?
    LVL 31

    Accepted Solution

    Heh... there are lots of them.. US Robotics, 3COM probably, several more...  You could even try a used 56k external modem of any brand and I guess you wouldn't suffer too much in terms of cash. Since the speed of dial-up connections seems to have topped out at 56k a few years ago, used modems with good specs, from people who have gone ADSL or so, may be around for cheap.

    Author Comment

    Well, I managed to get Dell to replace the motherboad and all is now well.

    A couple of items of note for those others who run into this error.

    When calling Dell tech support a number of times, my call was rerouted to India.  They tried to help.  It went soemthing like, " Did you try this?  Yes.  (wait a few minutes) Can you try this?  Yup, tried it, it didn't work.  How about this?  Nope, didn't work either.   Uh, sorry sir, I can;t hear you, you will need to call back.  What do you mean you can't hear me?  I hear you fine.  I am sorry sir, I can't hear you, you will need to call back."  I then proceed to go ballistic on their butt asking for their manager.  All of a sudden they could here me and were willing to help some more.  This same "I can't hear you ploy" was pulled on anumber of my buddies as well when they called for help.

    I chatted with the technician who replaced the board (Could have done it, but hey it's still under warranty)  Here is an interesting fact, I live in a city of 200,000 people.  The technician says they replace about 3 Dell mother boards a week for Dell Dimension 2400 systems.

    Take into account, how rude, persistent and argumentitive I had to be to get that technician to come out under the warranty and replace the motherboard, and it makes me wonder how more aren't getting to see the technician.
    LVL 31

    Expert Comment

    Makes you wonder, yes... Glad you got it sorted out!

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