BSOD Page fault in non paged area

I'm working on a friend's computer, he's had it for almost a year but all of a sudden a few days ago he started getting BSOD's while windows is loading. He says he hasn't installed any new programs recently. It happens right after the progress bar and splash screen before you get to the welcome screen. It's an 0x05 error and it lists no associated driver or file name or anything on the blue screen that i can see.

First i thought the ram was bad, i used memtest 86+ on all 4 sticks, only one of them came up with errors so now there are just 2 of the good 1 gig sticks in. Then i wasn't even able to boot up in safe mode. It was running in SLI, so then i decided to test the video cards one at a time thinking their vram was bad. The same bsod comes up if i try to boot normally, but i'm able to get into safe mode again. So now there is just one video card in and i can boot to safe mode (usually) without the bsod.

After getting in to safe mode after a normal boot fails, windows says the error was caused by the nvidia sata driver. So i go to nvidia's site, and i already have the most recent sata driver installed. I've already tried uninstall of current driver and installation of the most recent and older drivers, but it still gives the same error if i can get into safe mode.

There is an external hdd with the computer, but i disconnected it and all other peripherals and still same problem. Disabled startup services etc. Right now i'm running check disc, but i doubt that will fix the problem. So any ideas would be appreciated.

Well the check disc ran and rebooted, windows started up normally. Then i went to run ad aware and during it's update i got different bsod "IRQL not less or equal". And now it's pretty much just alternating between that and the page fault before the welcome screen.

see if you can restore it to a couple of weeks back and see if it happens.
It could be something updated itself and is causing it to happen.

Another important consideration is the possibility that the sata driver (or other) didnt go in correctly.
Nvidia drivers can be funny. I just went through this myself.
Nvidia drivers like to be deleted before upgrading.
Get a copy of driver sweeper and install it.
Then goto add remove programs and select the Nvidia entry. Click uninstall.
Depending on what is installed on your system you will be able to select what you want to delete.
Reboot and then run driver sweeper and reboot.
Then reinstall the driver(s)
Here is where you can get the driver package.
http://www.nvidia.com/Download/index.aspx