Suddenly today both outlook and word decided to start giving a new error message when I tried to launch: "could not create the work file. check the temp environment variable". After hitting OK it would launch. This is an odd one, and I am not sure of the cause (I have a theory I'll ponder below) but the solution was to run a check disk (chkdsk c: /F). Which fixed it nicely. I saw a number of security descriptor (AFAIK it was that, not an MCSE here) issues during the chkdsk, so I suspect something got corrupted.
The cause of the corruption may have been that over the weekend the IT team where I worked migrated everyone to a new domain via profile copy (doubt thats it) and deactivated UAC on the Vista users (think thats it). I am a UAC fan and turned it on again (using the msconfig tool) this morning and I think somewhere between being non-UAC admin and UAC admin the security catalog got confused causing the error. Just my pondering and I have no proof or way to test it (or interest in trying to get it to happen again) so take it with the pinch (handful, bucket, truck) of salt as needed.