We are using Office XP with SP2 running on Windows 2000 workstations w/SP4. I have an Excel file on a network share (Windows 2000 Server w/SP 4) which has special permissions:
* Two users have full control (let's call them Terry and Jerry), along with administrator
* All other users have read and execute permissions

Every couple weeks when Terry and Jerry (they don't use the file at same time) try to open the file, it says "File is in use by [themself]" and it's locked, though they haven't opened it since day before when it worked fine. I have verified no one else is in the file at all and it's absolutely not open anywhere else. Our antivirus software on server is not running a scan during the time and is not accessing the file (both server side and workstation side), nor are any backups running during the day. I have tried clearing temp files on the workstations and on the server share, I have tried rebooting computer, and also tried everything I could find on file locks in MS knowledge base, but to no avail. The only way they can once again use the file is to open it read only, then to do a Save As with another name. I have even tried to access file from server and to rename or open it there, but receive same error message. I can't find any common reasons for why it is fine for a while then randomly becomes locked. Sometimes it happens in a couple days, sometimes every couple weeks. Any help to correcting this issue would be appreciated. Thanks!