Parallels Virtualization and Automation Software

SYMPTOMS

Every website uses MS Access ODBC connection isn’t loaded and fails after some timeout.

CAUSE

Jet creates a temporary file when the engine is started. In doing so, it first checks the TMP environment variable and uses that path to define where the temporary file is created. If it doesn't see a TMP environment variable, it looks for the TEMP environment variable.
If TEMP is not defined, it then uses the Windows folder .

If TMP/TEMP is defined but points to a nonexistent folder, the error occurs.

Moreover, when opening the Access database through IIS or a Windows service, and when IIS or the service is running under the local system account, the TMP or TEMP system environment variable is used. When the Web services is started using a user account, the TMP/TEMP user profile environment variables is used.

RESOLUTION

Define a TMP or TEMP environment variable and assign the variable to an existing folder. If you are accessing the Access database from IIS, be certain to check the system environment settings rather than environment variables of the logged-on user. Also ensure that the IUSER anonymous IIS account has access to the temporary folder.

Additional information

Please see original Microsoft article as well.