Once an hour I am getting a login failure on the database server for a SharePoint 2003 server. The account(s) that are failing is the domain computer account for each of the web servers and the index server. It happens around the clock and each time it happens there are 8 failures - text below.
Event Type: Error
Event Source: Windows SharePoint Services 2.0
Event Category: None
Event ID: 1000
Date: 7/23/2009
Time: 11:02:38 PM
User: N/A
Computer: SharePoint1
Description: #50070: Unable to connect to the database Config_db on
SQLServer. Check the database connection information and make sure that
the database server is running.
For more information, see Help and Support Center at http://go.microsoft.com/fwlink/events.asp.
Chris Gideon from Microsoft gives a laundry list of possible reasons for this error on his weblog
http://blogs.msdn.com/cgideon/archive/2006/05/24/605454.aspx
I would be sure you have this update installed as one of the possible causes is fixed by this
http://support.microsoft.com/default.aspx?scid=kb;EN-US;900929
and it seems that many of the other possible causes relate to CPU load on the machine being too high and temporarily causing Sharepoint to be unresponsive. Can you run a perfmon and see if your errors correlate to high CPU?
Turns out the errors were generated by System Center Operations Manager. The Management Pack for SharePoint 2003 was running on this system and the associated service was running as the computer account (which didnt have access to the Config database). Stopping the service stopped the login failures on the database and the Event ID: 1000 messages that were occuring every hour.