Using Excel 2000 in a generic business networked environement

I have a speadsheet on a network drive with a number of people working from
the file. (It is not shared) When we link into another file it appears
correctly with the path name as it should with the drive and folder data.
ie s:\Main\Production\July\Month End.xls...

We are finding that when it is opened at times the link appears with the
server name and not the normal path name
ie \\ServerName\Main\Production\July\Month End.xls...

When this happens we have multiple links to the Month End file in the
listing of links. The incorrect link does not appear to be updating with the
update links button, you have to click the change links button and point
again to the correct file.

I cannot seem to find out how the links are changing. We can open a file,
and change all the links to be correct. Save and close the file. Reopen and
we have the problem.

Any suggestions are appreciated.
Thank you