Windows Explorer network copy broke!

Archived from groups: microsoft.public.windowsxp.general (More info?)

Windows XP SP2+++
I map a network dirve, then I can copy a file from my C: drive to the network
Z: drive fine. When I try to go the other way: copy from Z: to C: I get the
following
message after a few seconds.
"Error Copying File or Folder"
"Cannot Copy Transfer"
"The Specified Network Name Is No Longer Available"

After clicking OK to the message I can still browse drive Z:. This has
worked ok
in the past.

What did I break?? I tried restoring to a Checkpoint from several days ago,
but
no help. How do I reinstall Windows Explorer?
--
Don Turner