Comments by pankaj023 (Top 1 by date)

Correct
On a new server install the driver form http://www.microsoft.com/en-us/download/details.aspx?displaylang=en&id=23734[^]

Then in IIS application pool do this
As it turned out, the application pool that the site was running under had "Enable 32-bit applications" changed to "False". When I changed back to "True", the OleDb error went away.