Excel Save As problem - No Hoper

I don't hold out much hope for an answer to this since I see from other threads that this has been affecting users since Office 2000 - with no fixes forthcoming- Still here goes.
Office 2007, Excel (& Word) - one user (with the correct permissions) has suddenly stopped being able to "Save As" to any network drives. These are not shared files. User can save locally then copy file to the network drives (this is the current workaround). Temporary folder for auto recover is local drive. Allowed to delete files on the Network drive.
The two more than useless, error messages are:
"Z://........*.xls cannot be found check spelling or try a different path"
&
"Excel cannot save the file to this location. To save the changes and avoid losing data in your file, click the Microsoft Office Button, point to Save As and click Excel Workbook, and then specify a location on your computer"
DUH!

any answers please?
Thanks