XP wont boot

A few days ago my computer started acting funny. When I would leave it alone for a while normally it goes into a sleep mode, but wakes back up when I move the mouse. Well it started not "Waking up" anymore, so I would have to reboot after every time I leave the computer alone for a while. The last time it did it I got a blue screen saying it was dumping my physical memory due to a kernal stack error (I didnt get to read it all before it disapeared) At the bottom it told me to insert my windows CD and try repair. Well I grabbed one of my windows xp cds and starts trying to reinstall windows. Then I realize that I was using an evaluation copy, so I cancled the procedure and tried it again with an actual Windows CD. But now it wont get past the first boot screen that shows my motherboards logo. I can hit tab to go to my post screen, and delete to enter setup, but If I wait for more than a couple seconds it freezes there and I cant do anything.
I've searched online and all I can seem to find about windows not booting has to do with booting from a CD. Which I would do If I could get past that first screen. I dont think I've downloaded or installed anything new when this started happening, except from a windows update. Could that be causing the problem, or is it most likely a hardware failure? Any help would be greatly appreciated.

 

Have you seen this page at microsoft site? http://www.microsoft.com/windowsxp/using/setup/support/nostart.mspx

 

Much thanks for the link. After reading that I started playing around with my machine myself. In the end all I had to do was take out the motherboards battery, and put it back in. I remembered doing it to a couple school computers that wouldnt start up, and although it didnt fix the problem it got me far enough to be able to repair with the windows CD. Now I'm up and running again, so far without problems.

 

Things worked perfectly for a while. I event left it by itself so it would go into sleep mode a few times with no ill effects. But then today I came back to it after being in another room for a while and it had restarted. It was stopped on a screen that said something similar to

Boot CD:
Boot CD:
Insert windows CD and hit enter to begin setup.

I didn't try to repair windows because it works just fine, apart from this problem. So I again popped the battery back out, and put it in again. My dad thinks I might have a bad battery. I don't think thats the case, I think the only thing the battery has to do with it is that it resets the bios and who knows what else. I also remembered installing the latest winamp, so I've uninstalled it to see if that will make a difference. I'll update this as soon as I know something, but again, any help with whats going on with my machine would be greatly appreciated.

 

Well it worked fine for a couple of weeks, and then when I left it alone again last night it started acting up again and presenting the same problems.

 

For the small cost of a battery why not listen to your Dad.

 

Battery only affects cmos settings. Not the OS.

 

Because if the battery is indeed bad, then my system should be working at all I dont think. I think the process of removing and replacing just resets whatever is screwing up my machine.