Cant Drop, Trade, Use Without Crashing

My friend is stupid, and I dont know what he did but his comp always restarts or shutsdown whenever he tries to drop, trade, or use an item. Its really annoying because we do quests and then he gets logged out. Anyways he meets the system specs and I tried to fix his comp but I couldnt find any noticeable problems. I thought this might've been linked to the trojan he had earlier in the year. (His comp had a wget [webget] trojan and in my attempts to remove it, it crashed his comp because it had been there for over a few months.)

Get Mcafee antivirus, about the restart/shutdown. Does it give a BSOD of any kind? Did you turn off automatic restart of the system?

Run hijackthis on the system. If you want, post the log up for us to take a look at.

My wife's computer is having the same problem. At first, it wasn't playing at all. Kept saying something about the driver is no longer working. Then the computer shuts down & restarts. I updated the driver and it started to work. But now whenever I try to do something in her inventory or sell items, it crashes and then automatically restarts itself.

Any ideas?