A: Either the file you have is already on both drives and set with the read-only attribute, or Excel or the worksheet is infected with a virus that prevents you from saving files.

To cure the first problem, right-click the file in Windows Explorer and select Properties. You'll see some check boxes at the bottom of the dialog. If the read-only box is checked, uncheck it, then click OK. Repeat the process on any drive where the file is stored.

The second problem is more severe and warrants getting a copy of an up-to-date virus protection program, such as Norton AntiVirus, McAfee VirusScan, or Quarterdeck ViruSweep, with a current set of virus definition updates. (They are  available online from their respective Web sites.) Scan all the drives and any suspect  floppies, too. If you find a virus, repair and inoculate the affected file. Then warn anyone else who might have come in contact with the file. Keep the antivirus software loaded and running on your system at all times for continued protection.
 
 
 
                                                   SOURCE:  Zdnet and Computer Currents