80004005--Couldn't use '(unknown)'; file already in use
This error occurs when you use a Microsoft Access database and attempt to view a dynamic page in a web browser or in Live Data mode. Another variation of this error message is "80004005--Microsoft Jet database engine cannot open the file (unknown)."
The probable cause is a permissions problem. For more information, see Troubleshooting permissions problems. Here are some specific causes and solutions:
The account being used by Internet Information Server (usually IUSR) might not have the correct Windows permissions for a file-based database or for the folder containing the file. Check the permissions on the IIS account (IUSR) in the user manager.
You might not have permission to create or destroy temporary files. Check the permissions on the file and the folder. Make sure you have permission to create or destroy any temporary files. Temporary files are usually created in the same folder as the database, but the file may also be created in other folders such as /Winnt.
In Windows 2000, the time-out value may need to be changed for the Access database DSN. To change the time-out value, select Start > Settings > Control Panel > Administrative Tools > Data Sources (ODBC). Click the System tab, highlight the correct DSN, and click the Configure button. Click the Options button and change the Page Timeout value to 5000.
If you still have problems, see the following Microsoft Knowledge Base articles: