I was getting this error when I tried to publish the website from VSS2010 and this one is frustating because of time consumption then I started to looking on the net almost one day I spent in google and tried every solution but nothing works, finally I got the suggestion and it help me to work. The culprit was McAfee antivirus.
Issue
While publishing the build Object reference not set to an instance of an object error
Resolution
Disable the McAfee antivirus and it works.
Here is the link to refer:
Hope it will help others if they are getting the error.