>>Hmmm ... can you COPY FILE from within VFP?
>Yes, I can COPY FILE. Also, the network drive where I'm trying to COPY TO is actually a drive on the local machine. If I go to the local drive instead of the drive mapping, I can execute the COPY TO successfully.
>
>I just noticed that if I open up a "My Computer" window with the list of local and network drives, try to COPY TO until I get the error, and then glance back at the "My Computer" window, the network drive has a red-X on it. If I single-click on the network drive, it reconnects. So, it appears to be disconnecting for some reason (just like the VFP message indicates)?!

There's a Windows setting (not sure whethere it's local or on the server) that controls whether persistent drive mappings are retained full-time. IOW, mappings may connect only when accessed and may time out.

Sounds like you're hitting a timeout.