Runtime error 8021?

[stargategfx]

Just ruined a nice piece of teak with my Shopbot Alpha.
Even worse was the fact that it was for my own boat!
Getting runtime error 8021 "Internal error retrieving device control block for the port"
I'm running Windows XP, Shopbot 3 v3.5.7 to a spindle equipped 60 x 120 Alpha via a powered USB hub.
The system has been pretty stable for a couple of years but has been acting up lately.
Anybody experienced this error?
Here's my boat blog in case anybody is interested www.catalinathirty.com

[beacon14]

If a formerly stable system is starting to act up, and you have not changed anything recently, the first thing I'd suspect is the computer. I had similar problems a few years ago, turned out the computer's memory card was defective and was starting to fail.