Solution by Event Log Doctor

We got this error on a 64-bit Windows Server 2003 with SP2.

You can run the MDAC component checker to ensure that all drivers that part of MDAC are installed and have the correct version:

http://www.microsoft.com/downloads/details.aspx?FamilyId=8F0A8DF6-4A21-4B43-BF53-14332EF092C9&displaylang=en

It didn't reveal any problems on this machine, and database connectivity was not affected.