Cannot save to network drive but can to local drive

Excel 2007 SP2 on a Win7 Pro machine to a shared drive on a Server 2003 >
when trying to "save as" or "save" a renamed workbook
this message appears:
'network drive\folder\filename.xls cannot be found. Check your spelling, or
try a different path."
permissions and path are correct and there are no illegal characters. the
name can be very simple with no success.
but the file can be saved to the local hard drive and then copied to the
network location.

any ideas? all ideas are welcome. thank for your help in advance.