From the error message, it is clear that some DBCC command was being executed when the error occured. In SQL Server 2005 and above, during DBCC command execution Database Snapshots...

Did you try starting SQL Service in Single User mode from the command prompt?

Usually it gives the right picture there.

Try enabling the WMI logging and see if it helps. Refer this and this.

Check if sqlsrv32.dll is missing. You may find this post[/url] useful.

Seems to be a problem with MMC. Why not connect to the instance using SSMS?

You can download SSMS from here and install in on the same server.

Hope this helps!

Using Windows Authentication only controls the access to the instance. Authentication level will not have any impact Ownership. Having SA as the owner even in this case will not have...

The "unyeilding thread...." on the SQL instance lead to the failover.

Please refer

http://support.microsoft.com/kb/891268

http://support.microsoft.com/kb/810885

The System Event Log, SQL Server Error Log and the Cluster Log (c:\windows\cluster\cluster.log)...

Try adding an output file to the file system by modifying the job step properties. This should give more detailed information.

Please check the open connections/performance of the Server to which the job points to. Most likely the server is busy when the job fails.

SQL Server is running out of memory. Try restarting the SQL Service. This will resolve the issue.

If this issue reoccurs try increasing the memory_to_reserve by using -G switch as mentioned...

As mentioned earlier, the backup file format is not usable and the file needs to be deleted. After that try taking the backup with INIT or FORMAT options in the...

Did any of the configurations change?

Try using the command line OSQL.exe to connect and troubleshoot

If that does not help try starting the SQL Server from the...

You may try some of the options mentioned here

You may try increasing the RAM/Page file allocation on the host.

Ref: http://seer.entsupport.symantec.com/docs/198240.htm

You can remove the BUILTIN\Administrators and add the required AD Users/Groups to SQL Server and grant them appropriate rights.

Hope this works !!