RDC occasionally freezes

My setup: I'm connecting from a home OSX 10.2.6 to my office XP pro.
The connection is via a router, cable modem and VPN. The Mac is an
iMac 400 mhz.

Problem: RDC usually works perfectly. Ocassionaly however, RDC just
freezes. My only fix is to quit RDC then restart RDC. I can usually
work from 15 minutes to 2 hours before RDC freezes.

Is there anyway to analyze the problem? Or better yet, is there a fix
or workaround?

Thanks

Mitch