I just got a new computer a month ago that worked perfectly. We had the "Geek Squad" at Best Buy put all out hardware updates (RAM and video card) Games ran smooth and we had a fast internet. About 2 weeks ago, we go a message that hal.dll was missing or corrup, so we did a complete sysyem restore. We installed all the hardware software back on and the computer seems very slow and games will freeze up almnost 80% of the time we try to play them and C+A+D doesn't work. We have all the latest patches for each game. I have even tried windowed mode on most games and nothing.

Comp specs that I know:
XP HE (we updated
HP Pavillion
AMD 3000+ processor
Nvidia GeForce 6800
1 gig of RAM (I don't know whether it is duel 512MB or single)

Ganes that freeze:
Sims 2 DVD
SimCity 4
Star Wars Battlefront
Battlefield 1942
Battlefield Vietnam
MoH: Allied Assult
Far Cry

Everytime that the computer crashes and freezes, the "Windows has suffered a severe error" message pops up at start-up and says that Nvidia caused it. I have downloaded and installed the lated drivers and it still does it. Any ideas?