"lock request time out period exceeded" Error When Trying to See DB Hierarchies

It was being caused by a perpetual rollback of a transaction. Had to eventually restart my server cluster

Excluding Harware consideration, perhaps you need to run the script to check what are the activity withholding the SQL Session, one of the common scenario is not to use an Implicit transactions Option in SQL Server Management Studio.

I got this problem when I began an explicit transaction in which I created a table in tempdb from a script running in another database (not tempdb). When I committed the transaction, the commit didn't seem to release the lock on the table I had created in tempdb.

Thanks to this page, I USEd tempdb and executed DBCC OPENTRAN and got the SPID of the connection to tempdb that was causing the lock. Then I KILL <SPID number> to kill it.

Not very graceful, and I lost all the information in the table I had created in tempdb, but that was OK in my case.