I'll second checking what actions are listed on the menu - before I reinstalled to XP my machine used to do it a lot. I tend to keep the programs in the list to WinZip and a secure deletion program.

The main thing that is bugging me is on my computer at work - I have folder on a collegues computer as a mapped drive and when he switches it off and I do a "save as" it pretty much locks up for ~2 minutes. Opening "My Computer" and it shows it as disconnected...

Gareth