I have one server running SQL Server SP 2 and one running SP 3. The SP 3 box has the error and the SP 2 box does not. I don't know if this is causal or coincidental yet. But I know that the databases are exactly the same and the SP 3 box is much, much more powerful.
More specifically, when the SP 3 box connects to the SP 2 box, though Enterprise Manager, it generates the error. When the SP 2 box connects to the SP 3 box, it does not.
So it seems to be a problem with the Enterprise Manager GUI and not the underlying DBMS.