I am having similar issues with my SQL 2014 with WinServer 2012.

When I do as suggested, this is the error I get:

Msg 7399, Level 16, State 1, Line 3

The OLE DB provider "OraOLEDB.Oracle" for linked server "xxxxx" reported an error. The provider reported an unexpected catastrophic failure.

Msg 7330, Level 16, State 2, Line 3

Cannot fetch a row from OLE DB provider "OraOLEDB.Oracle" for linked server "xxxxx".

Any suggestion on what to do next?