MN-510 Problem - HELP!!

I am having a problem with a PC and an MN-510 USB
Adapter. Everything has been working perfectly for
months, and then today, on one of the PCs, the adapter
just stopped working. The adapter works fine on another
computer - but on one of the PCs, after a reboot, the
adapter works for about 5-10 minutes, and then the
connection speed drops to 0.

I have no idea what it is, I have used the USB ports on
the back of the PC, as well as ports on a powered USB
hub. All other USB devices work properly.

Is this a case where reinstallig the MS Broadband
networking components might help? I have no idea what
the problem could be (also, the adapter is about 20 feet
from the hub, so there shouldn't be any problems at all
with the wireless connection - they are in the same room).

Thanks in advance for any help that can be provided.