Explorer.exe failed to initialize

[Nomad84]

I am trying to help my cousin over the phone (115 miles away) and not having much luck. He is running XP and gets the following error message when he boots:

Explorer.exe application error. The application failed to initialize properly (0xc0000022). Click OK to terminate the application.

When he clicks OK, it goes to a blank screen. Ctrl-alt-del brings up task manager, but the list is empty. He can boot into safe mode, but I wasn't sure what to tell him to do at that point. I've tried to do a search of that error code, but I've come up empty-handed so far. Does anyone have any suggestions?