BSOD "IRQL not less or equal" w/ nvidia driver issue

[bjj8383]

HP Pavilion Notebok dv6338se
Windows Vista Home Premium build 6.0
AMD Turion 64 X2 Mobile Technology TL-56
NVIDIA GeForce Go 6150
958 MB RAM

I cannot log into my computer, except for in Safe Mode, because I'm stopped by a Blue Screen of Death, with the error "IRQL_NOT_LESS_OR_EQUAL". The Stop Codes seem to change every time.

I've read that some people encounter this while playing a large computer game. I first experienced trouble while playing Eve Online, which I'd succesfully had installed for ten days. I uninstalled it and ran the standard battery of antiviruses and anti-spywares, which didn't help.

Twice (in safe mode) I've gotten a message saying the problem is from an issue with "NVIDIA nForce SATA Driver." It also says the problem has been dealt with in Vista Service Pack 1, which I never bothered to install before. AutoUpdate won't open for me in Safe Mode, so I downloaded it myself. After 5 hours of installing and configuring, I got the message that the pack FAILED to install and spent several hours waiting for my machine to revert to its old settings.

My computer model comes with the old NVIDIA GeForce Go 6150, which NVIDIA doesn't even bother to update for anymore. So, no new drivers form their site. I downloaded what drivers & etc I could find from the HP site. I also tried to download more from Microsoft directly, but now I'm getting a message saying that my copy of Windows can't be validated.... after I just downloaded the service pack the other day from their site with no problem. They offer a sollution for this that I can't execute in safe mode.

After I got that battery of drivers, my computer actually managed to START to load my normal desktop... before a generic Blue Screen popped up. The next Blue Screen that came was the familiar IRQL error. I also ran the built in memory check, which found no problems.

So. There's my plight. Any suggestions?

Side question: If this is indeed a driver/video issue, why on earth did it so suddenly appear, and why is it so bad that my computer won't even let me start it normally? Makes no sense to me.