Windows Office Permissions with Windows Server 2003

Whenever users try to save a Power Point or Excel files on the server, they get a “this is a read only” message. I “solved” the Excel problem by upgrading permissions levels to administrator (obviously not an ideal solution – but at least we remain productive). With .ppt files, I can’t even save when I sign on as the administrator. I can move the file to a user’s computer, modify and then copy over the old file but not a direct save. I check the read-only status – which was on – and turned it off but it did not help. We are using Office 2003 applications.