Help-Computer's restarting itself

k, not sure what info you need to help me but here's what I have right now.
Running Win xp w/out service pack 2 installed. Thursday the computer ran fine but Friday the computer started restarting itself randomly, sometimes it will restart almost immediately on reboot and sometimes it will run for a while. I turned off the auto restart option so that I could get the error message. The message is
PFN_LIST_CORRUPT

Technical information
0x0000004E (0x00000099, 0x00000000, 0x00000000, 0x00000000)

Also about a week prior a second hard drive was installed on this computer. It was a replacement (there was one there before so 2 drives is not a new thing) I'm not sure of the specifics of the drive, I wasn't here that day. Any help would be appreciated! Any ideas on whats causing this?
Thanks
Tia

 

http://msdn.microsoft.com/library/d..._6c89b2a4-d5a9-4585-a3d1-87bc7fc39c82.xml.asp
http://search.yahoo.com/search?ei=utf-8&fr=slv1-&p=pfn_list_corrupt

Somewhere you have a bad driver causing a "Page Frame Number" error.

 

Well, I'm was pretty sure that the messed up driver was nvidia driver, so I reinstalled it. Then the compuiter came up with a new error.
0x0000007E (0xC000005, 0x8054EC838, 0xF9483A94, 0xF9483794)

Okay, Thanks to Brownizs I've found the error, but I don't know how to fix this one.
0xC0000005: STATUS_ACCESS_VIOLATION
A memory access violation occurred.

Help please!
Tia

 

you might update your system at windowsupdate.com .. also might try reinstalling your video drivers with driver cleaner pro

 

Just get the critical updates don't bother with the rest unless you use windows media player, etc