Under the General Settings for the Virtual server  you can set the Default Time
Zone. Is that set? How does it compare to the user  and the server's time
zones?

This sounds strange, but I had something similar to this. The way we fixed it was to have the user  go into Outlook Web Access and through the OWA options select his proper timezone. It fixed it for him (don't ask me why.. or how this is connected)

If you do try this though, please give feedback if it resolved the problem.

About 10 minutes after I posted this, I
figured it out. It was the Regional Settings on that particular SITE
that was incorrect. We're in Indiana and just recently moved to
using Daylight Savings Time...the user  still had the TIME ZONE set to
Indiana (East)! It's not like we've been on DST now for almost a
year! Tells you how much that user uses their site?