CAI 302 download woes

I have an IBM Thinkpad with no serial port. For downloading from an
LX-5000, I have used a Belkin USB to serial adapter. It has worked fine.

I now am trying to download from a Cambridge 302. When everything
works, it takes roughly a minute to download 3 minutes of flight data
(and at least a minute just to change the name of the pilot). When
everything doesn't work (about half of the time), you have to reinstall
the Belkin software before you can establish another connection.

Gary at Cambridge has not been able to help. Nor has the local
college-age computer wiz. Anyone have any ideas?

Greg Arnold