I have the same problem, except that it is one machine.
I have two profiles, an admin and a user. The user profile is showing the same symptoms as you describe, AND, some dialog boxes don't display text properly too!
I just tried cresating a new account with an admin profile, and that has the same symptoms too, although the one I use, with an admin profile is fine.
These problem started after I uninstaled .NET, which also caused a load of other stuff, like MS Office not working.
I have followed various other suggestions, like re'regsvr32'ing various dlls without any sucess.
I also did a windiff (file comp utility with visual studio) on the entire registry files from my profile and the not working one. It couldn't find anything (which in itself is strange as I would expect the current user key to have at least SOME differences!)
Did you resolve this problem wapper? Its weird