Bob - I'm with DF on this one -
but ? take a look in real time what your machine is doing -
http://www.sysinternals.com/ntw2k/source/filemon.shtml
and keep a log.

Sounds to me based on the speed, or lack there of, that you're doing a complete low level directory traversal each time a file is requested.

Virus scanners can be reconfigured to NOT look in certain directories or shares.

lemme know how it turns out ?
regards [Bill]