I've had it happen when some other OS process had the port tied up. In one particular case, I had two Squeak images running, and the other Squeak image had the port. Once it happened, quitting the other image (if that was *all* I did) didn't seem to help. So, my usual solution is to: (1) save image, (2) quit all images, (3) make sure nothing else is running that might have the port, and (4) relaunch the single image.

At least on unix/linux it's easy to check if some process is listening on a particular port:

netstat -an | grep 8001

Windows 2000 understands 'netstat -an' as well - unfortunately there is (usually) no 'grep' available.

Might be easyer to check what's going on than quitting all apps.

Christian