I'm not a sysadmin, but I play one on TV: I'm trying to fix a problem for my mom's tiny non-profit company's server. I set up a Windows Server 2003 machine as a domain controller and file server. Everything has been working well for a few months, but lately when she tries to save changes to a Word (Office XP) document stored on the server, Word will intermittently report that the file is read-only. Saving to an alternate file in the same directory works, and when she closes Word and re-opens the original document, it'll save changes just fine. No one else ever has these files open.

I've checked security and share permissions, and everything's OK. We've tried rebooting the server, but the problem continues, but intermittently.

I have no clue what's going on. Help!