Excel causes error on open - " cannot be accessed. The file may be corrupted, located on a server that is not responding, or read-only.

This error message appears, usually the first time the Excel file is opened

" cannot be accessed.  The file may be corrupted, located on a server that is not responding, or read-only.

The quote is part of it.  I have to say close, and then, without closing Excel, I can then reopen the file and it will come up fine.

Can anyone suggest a reason?  I don't think it's corruption, since the file opens fine.  I don't think it's a network problem or server not responding, since this is only affecting one person (who of course, probably deals with the most Excel documents in the organization).

This is a Windows 7, Office 2007 Professional SP2.

Thanks