Windows 7 crashes on startup, "Attempt to reset the display driver and recover from timeout failed"

Right, so I'm using an HP laptop, and it seems to be consistently crashing on startup, with a bunch of strange coloured lines and pixels before the login screen appears. I usually dont even get a BSOD, but I did just once, with the error code 0x000000001E and the error message "Attempt to reset the display driver and recover from timeout failed".

I'd had this problem using Windows Vista as well, and thought an upgrade to 7 might fix it, but apparently not. Listing my computer specs below in case they're of any use.

HP Pavilion dv9830us

OS: Windows 7 Home Premium 64 bit edition, formerly Windows Vista Home Premium 64 bit edition

RAM: 4GB

Processor: Dual Core Intel T5550, its a 64 bit processor, I believe.

Video Card: Nvidia Geforce 8600GS (mobile), 512MB VRAM.

What I've tried so far:

Every edition of Nvidia drivers that I can find for my card, using 3dguru's driver sweeper each time I install a new one. I've used the new 195.39 beta drivers as well, and those did work for a few hours. However, when I shut my pc down it wouldnt start up again, reverting back to the same crashes.

Flashed my BIOS to the latest version as per HP's driver page for my laptop.

Checked that my chipset drivers are up to date.

Disabled all Aero effects (just in case that was the problem)

Basically, if my PC has an Nvidia driver installed on it, it crashes. If I go to safe mode, uninstall the video driver, it boots up fine in normal mode with the regular VGA driver. When I then install an Nvidia driver again, back to the crashes.

Since I do tend to use my PC quite a bit, any assistance is appreciated.

Thanks in advance.