We're getting the error "The user does not have permission to perform this action" during times of heavy load (regularly, when a trim job occurs). The error clears up when the service accessing sql server is restarted, so it's obviously not a real permissions problems.

There's a possibility that the problem is occurring when we're trying to query dm_tran_active_transactions and sys.dm_tran_session_transactions.

Any ideas of good places to start looking?

thanks for any insights...