Microsoft JET Database Engine (0x80004005) Could not use ''; file already in use.

This error usually happens on Windows NT/2000/XP when your database file or database folder doesn't have write permissions. You can often solve it by following these steps:

1. Right-click on the project folder on your disk and select Properties.
   
2. In the Security tab add Internet Guest Account and set the Write permissions checkbox.
   

For more information, refer to: http://support.microsoft.com/default.aspx?scid=kb;EN-US;q174943