I found the same issue in SQL Server 2012 SP1.

It's definately a UI bug and believe Microsoft should do something.

Because of that, I spent lots of hours to figure out...

Actually I'm in a shopping a new performance monitoring tool like you. I've been using IDERA SQL Dm (Diagnostics Monitor) for around 3 years.

But it's not that much intuitive and...

I've met the same error "Network path was not found" in SQLH2 log.

In my case it's fixed by starting Remote registry service in the target server.

Try that.

What I found is install Oracle 64bit & 32bit both clients in the 64bit system.

That way you can design & test on BIDS (which is using 32bit OraOLEDB) and run...

To add SQL Server 6.5 linked server in SQL Server 2005 (especially 64bit), ODBC is the only solution what I found so far.

The steps are little bit tricky as well.

Add...