conn="Provider=MSDAORA.1;Password=U;User ID=U;Data Source=U;Persist Security Info=True"
Verify that a TNSNAMES.ORA file exists and is in the proper place and accessible. See the operating system specific manual for details on the required name and location.
Check to see that the service name exists in one of the TNSNAMES.ORA files and add it if necessary.
Make sure there are no syntax errors anywhere in the file. Particularly look for unmatched parentheses or stray characters. Any error in a TNSNAMES.ORA file makes it unusable.
If possible, regenerate the configuration files using the Oracle Network Manager.
Thanks! I ended up having to talk to my db Admin to get a copy of the SQLNET.ORA file also, due to encryption on the system, but you got me started in the right direction when I had no idea where to go.
I hope this helps the original requestor as much as it did me.