Excel Error "The file *.xls may have been"

Hello:
I am getting an internittant error when saving a file in Excel 2003.
The files are being saved to a Novell 6.0 sp5 server. Excel has the latest service pack and patches. "The file (lists filename here) may have been changed by another user since you last saved it. In that case what do you want to do? Save a copy or Over wright changes.

Microsoft had a technote for Office XP and this error, but the registry changed for Office 2003. Has anyone seen this?