Laptop doesn't boot sometimes

It's not likely stiction.  Since you're only getting a black screen and no BIOS report, the computer isnt starting the POST sequence.

It sounds more like a failing power supply.  There is a POWER_GOOD signal that the motherboard monitors and if it's not there, the motherboard will not boot.  If the power supply has gone marginal, it won't be good enough for the motherboard to allow starting the POST.  The fan though doesn't really care simply being a DC motor.  Give it a little voltage and it'll spin despite the power supply being flakey.

I agree with thinkpads_user, you'll might want to run tests to see if the hard drive is dying.

Thegof... are you saying that my laptop's 19VDC power supply is failing or the power circuits in the mobo?  Remember, this is a laptop.  On the other hand, I suppose if the battery was going, it might pull the power down a bit more than it should, leading the mobo to think that there wasn't enough voltage.

This would be easy to test... measure the voltage output of the power supply, make sure it's 19VDC.  Then, measure the voltage after connecting it to the laptop.  If it's dragging it down to, say 17V, I could try removing the battery and see if it goes back up to 19V and the problem goes away.

I'll have to reboot a handful more times and see what I get on the screen during POST on good boots... I'm pretty sure I've disabled the splash screen and maybe I've even switched it to the fast boot, where much of the POST is bypassed.

If that all checks out, then I'll have to presume that it's the hard disk.

Doesn't XP have a boot log?  How do I get to see it?

Thanks.

Al.

On second thought... I'd have to say that the battery must be good... when I go off AC and run purely on battery, I get over an hour and a half on a full charge.  Not bad for a laptop built in 2006!

So how do I test this theory and why would the problem be intermittent?

Try a boot CD.  Windows or Linux.

Just get to the boot screen.  

Or try Knoppix http://www.knoppix.org/  This is a Live CD and you can boot and run applications and you won't affect the hard disk.

Or get the UBCD http://www.ultimatebootcd.com/

Download links are the icons at the top of the page above Overview.  Browse the page and see what utils are there for you.  Check the memory and hard disk utils especially.

Make the CD and boot from it.  

Then test the hard disk with the correct manufacturer's util for your hard disk.  Do the long test.  That will most likely tell you if your disk is corrupt.

If you can successfully boot each time from the CD then it could well be the hard disk is the problem.

If you can't there's a hardware problem which probably does not involve the hard disk.

I'm not getting a POST.  I believe it's temperature dependent.  Last night, after running all day, I powered the laptop down and then immediately tried booting it.  Nothing at all from the BIOS.  It takes 5 seconds, and not 10 as I reported earlier, to get it to power down.  I repeated the attempted boot at least a dozen times and each one failed.  Completely black screen.

This morning, it powered up on the first try.  The moment that I pressed the power button, I could hear the HD spin up and one of the two fans.  First, there was a 1/2-sec bit of text at the bottom of the screen, then about 5 seconds of "Press F11 if you are having trouble" or something like that.  Then blank screen for a second or two, then the Windows XP splash screen.

I'm not going to push my luck and try it again until I'm done with the laptop for today... maybe I'll try rebooting after it cools, if it doesn't power up immediately after shutdown.

I'll get a few of those bootable CD's (I know I already have a bootable BartPC and MemTest86+) and try them too, but I think thegof is is probably right... if there's no BIOS activity at all, then it's a far lower level problem than the HD, unless... stiction in the HD could drag the power down enough to prevent the mobo from proceeding with POST.  If that's the cause, I would think that putting a bootable CD in the optical drive wouldn't work (I know... change the BIOS to boot first from optical) until I disconnect the HD.  I think I can borrow a 2.5" SATA drive from work or maybe even find an old one being thown out.

Thanks.

I have done all I can without sending the laptop in for repair and I could not afford to be without it the last few weeks.  Now, I'm able to send it in for repair.

I have determined, empirically, that it's not related to heat.  It now  takes 30 to 40 attempts to boot regardless of whether the laptop is cold or warm.  I have resigned myself to the fact that it will probably need a new motherboard.  If I could find out what the voltages should be at various test points, then I might be able to figure out which part on the mobo is defective.

Meanwhile, I'm 99% certain that the problem is the motherboard power circuits.  Can you make this active again and I will split points.  I think it's valuable for readers to know that it's not the hard drive.

Sorry it took me so long to deal with this issue.  I still haven't completed fixing it, but I've pretty much decided it must be the power circuits in the mobo.  When I reached POST, the system continued to power up... the other 30 or 40 times, all I got was a fan and a blank screen.  If I could get the repair manual from Gateway (ha!) I could probably fix it.  I have no idea what the voltages should be and randomly replacing parts in the mobo is a time-consuming repair method.  I don't even have a schematic, nor, I think, will Gateway ever give me one.  There's a place on ebay that fixes laptops for a flat $175.  For a $1999.95 laptop (in Dec 2006), I think it's worth it:  17" WXGA, T7200 dual-core CPU, DVD burner, 2GB, 256MB non-shared video RAM.  Thanks.