I am not ure if anyone else has seen this issue or can advise:
Yesterday one of our web servers began failing to connect to SQL Server (physically separate box) and failing with the error
Microsoft OLE DB Provider for SQL Server error '80004005'
[DBNETLIB][ConnectionOpen (Connect()).]SQL Server does not exist or access denied.
This happened spontaneously and not in response to anything new intalled, hotfix, reboot etc.
When the web server is rebooted it is able to connect to Sql Server normally for *about* a minute, then the problem begins to reoccur. It does not repair itself and the only thing which gets it working again is another reboot, but then only for a minute or so and then fails again.
The Cliconfg utility was checked and the protocol being used is TCP/IP. I have tried adding Named Pipes into the list but to no effect.
I am not certain at the present time if this is a network or IIS issue. The Sql box remains online at all times. Watching it in Profiler, when the web server is rebooted connections come through as normal and then simply stop after a minute; there is no one command which is always the last to run.
The Sql server will accept enterprise manager connections externally and from IIS running locally here, so the issue is only *between* the IIS box and the SQL box.
The Data Centre we use are also experiencing this issue on at least one other IIS/SQL box combination however we have other web and Sql boxes there which are unaffected.
I'm about to give in and move every website from this web server onto another one, but that will take some time as it's about 40GB of data to move.
If the netbios, dns name, and IP address all fail to connect then it would have to be a network issue. Any time i have ever seen an access denied error the sql box was either down or the network connection disconnected. Are your running any firewall software? You might also try using odbcping to test the connection.