On SBS 2011, you may see this repeated a lot in event logs:
Session "WBCommandletInBuiltTracing" failed to start with the following error: 0xC0000035
According to Microsoft, this can safely be ignored. However, many times these events will crop up so often as to eat up server performance.
To fix, open an administrative command prompt, CD a la:
cd C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\14\BIN
and run
PSConfig.exe -cmd upgrade -inplace b2b -force -cmd applicationcontent -install -cmd installfeatures
If you see a message which says SPWriterServiceInstance would not start, and/or if the Sharepoint VSS Writer service is disabled, try this:
stsadm -o registerwsswriter
which should get the VSS writer set up and going, and then run the PSConfig above again.
References: