In the event viewer I see "Event 5586 (SharePoint Foundation) of severity 'Error' occurred xx more time(s) and was suppressed in the event log" many times in a day. It shows an event id 2159 and a task category 59.
I've tried the following with no success:
Open the SQL Server Configuration Manager
Browse down to SQL Server Network Configuration – Protocols for <namedserverinstance>
Right-click “Named Pipes” in the right pane and choose Enable
Rebooted the server.
Any more suggestions?