Computer hangs when opening a file

One of my users is experiencing a problem…
His wording….
“When I try to open an existing excel spreadsheet or Word document while the computer is not synchronized to the system through the VPN and in each case the computer locks up. I get ?Word (or Excel) Not Responding?. Seems to be fine if I synchronize. It does not seem to matter whether the file I am trying to load is a synchronized file (i.e., in ?My Documents?) or not.”

This occurs when the computer is NOT on the network, either VPN or in the office.

Any ideas would be helpful.