Cannot initialize the data source object of OLE DB provider "MSDASQL" for linked server "(null)"

The problem comes because the Temp folder of the User under which the SQL server service is running isn't accessible under the credentials which the query is running. Try to to set the security of this temp folder with minimal restrictions. The dsn that gets created every time you run an openrowset query then can be recreated without any credentials conflict. This worked for me without any restart requirements.

We ended up restarting the database server and that seemed to solve the problem. Maybe the files were getting locked somehow. We'll never know for sure though

I had to download and install "Microsoft Access Database Engine 2010 Redistributable" available here.

"The cause of this issue is that there is no 64-bit ODBC text driver installed on your 64-bit Windows server 2003 actually. The 64-bit MSDASQL just provides an OLEDB/ODBC 'bridge' that allows applications built on OLEDB and ADO (which uses OLEDB internally) to access data sources through ODBC drivers." Source