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Why does my second ODBC-ODBC Bridge connection to Microsoft Access hang?

Simultaneous Easysoft ODBC-ODBC Bridge connections from UNIX to the Microsoft Access ODBC driver can hang. We think that the Microsoft Access ODBC driver DLL may contain some shared data that is incompatible with a multi-threaded ODBC-ODBC Bridge server. You can work around this problem by changing the ODBC-ODBC Bridge server to run multi-process.

According to Microsoft's web site:

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Known Issue: ODBC Jet driver in multithreaded environments
Component: ODBC Jet driver
When running in a multithreaded or stress environment such as IIS, it is recommended not to use ODBC because
of issues with threading in the driver as well as the Jet engine. The recommendation for this situation
is to work with the OLE DB provider for Jet.
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To make the ODBC-ODBC Bridge server run multi-process instead of multi-threaded, use the ODBC-ODBC Bridge server administration interface (http://mywindowsmachine:8890). Choose Configuration > Change > MultiProcess, and then choose Submit. If the ODBC-ODBC Bridge server configuration page, has an AutoUpdateConfiguration checkbox and it's not checked, restart the ODBC-ODBC Bridge server service.

Update According to Microsoft's web site, JET 4 is now thread-safe.

To check whether you have JET 4 or later, choose ODBC Data Source Administrator > Drivers and check the Microsoft Access Driver version. If you have version 4.xxxx or later, you should not need to switch the ODBC-ODBC Bridge server into multi-process mode.