Mark,
I'm sure you've eliminated this as a possibility, but I'll ask anyway - is there any chance that another user/job/process has the table open exclusively?
Also...I can't recall the specifics, but I know that a long time ago, VFP sometimes generated misleading error messages when it couldn't find a file on some networks and NT configurations. So if you were opening the file with macro substitution and/or a UNC, and VFP couldn't find the file, it would generate a different message than 'file not found'. Just figured I'd mention it.
Kevin