"Remote procedure call failed" with X3/Word 2007/Vista

I have an off-site user (using Cisco VPN) who switched to X3, Office 2007, and Windows Vista all within a short period of time. He has been experiencing problems inserting references. When he tries to insert a reference, there is no response at first, then he gets a “remote procedure call failed” error message (no other info in that message). When he cancels out of the error message, the reference has been inserted. This happens every time. Also, he cannot format a bibliography ever. That appears to crash his machine entirely. This only happens off-site on the VPN.

Any ideas? TIA.