I just came into the room to see if anyone else was experiencing any IE troubles lately. There are a slew of people I know who are having problems with their IE6 after the latest round of upgrades.
Not ten minutes ago I had to delete the ntuser.dat file for an end user of mine, remove their profile from the computer they work on, and have them log in again. That fixed the problem which leads me to believe there's some corruption going on in the .dat's.
Try to roll back IE to pre-SP1 or remove any recent windows updates for IE you've installed.
Wedo