could you please give me a bit of advice.
We have one server with 2 SQL Server 2008 R2 instances running on it. Yesterday we installed SP2. Today one instance from time to time refuses to accept new connections.
The symptoms are:
1. If the connection is open, everything works perfectly. E.g. if we have open the SSMS window, it has never ceased to work: you can enter different queries in it, they will work.
2. If the operation requires new connection to be established, it fails. We get the meassage "A severe error occurred on the current command. The results, if any, should be discarded."
3. It can be cured for some time by the instance restart.
4. The second instance works perfectly.
I do not know what causes this error. I cannot reproduce it.
No traces in error logs. I have no idea where to look and what to search for. DBCC CHECKDB on master gives no errors.
Any ideas will be really appreciated.