Make sure that you have installed all updates and servicepacks for both
Windows and OS. It is going to be difficult to determine the problem here as
this could be anything from a bad network path (Switch or NIC problem) or it
could be a problem due to HDD access being slow with temp files not being
created or deleted sufficiently quickly.
First I suggest that you clean out all abandoned temp files in your User
Temp folder. With all applications closed, the user temp folder should be
empty: delete everything you find in there. Then on the device acting as the
'file server', with all applications closed AND all other users shut down,
search for all abandoned temp files and delete them all. Most should be in
the folder(s) used for storing the documents, but you may find some in the
root too.
Then to try and find the problem, try a couple of tests over a few days.
1. Work exclusively on your local drive. Copy files to and from the 'file
server' location and do all editing and saving on your local machine.
2. If that is unsuccessful, switch Word to compatibility mode and test
again.
Terry