Why don’t you use a network location to save your excel files, try to restart windows in safe mode with network support and then try to save your excel files.
For more information about how to start windows in safe mode or about how to perform a clean boot, click the following article number to view the the Microsoft knowledge base:
192926 (http://support.microsoft.com/kb/192926/) How to perform clean-boot troubleshooting for Windows 98
267288 (http://support.microsoft.com/kb/267288/) How to perform a clean boot in Windows Millennium Edition
281770 (http://support.microsoft.com/kb/281770/) How to perform clean-boot troubleshooting for Windows 2000
If the Excel file saves after you restart Windows in Safe Mode, try to resave the file again. To do so, click Save on the File menu.