Problem with fiber link locking network segment...

I am about to jump on board with someone that has an ongoing problem.

Two buildings connected by fiber and D-Link DFE-855 media converters on each
end.  Both DFE-855 units connect to 3Com 16-port hubs which are part of a
Windows 2000 Server network.

The fiber is about 500' long.  Every other day, all the computers in the
remote building lose their connection with the server in the main building.
You can't ping anything or renew the IP.

When you disconnect the power from the DFE-855 at the remote end and power
it back up, connectivity is restored.  Does this sound like a D-Link
hardware issue?  I have had nothing but problems with D-link switches so I
was wondering if the same shabby quality is in their media converters.

I'm open to any feedback or suggestions.

TIA