Soultion
Follow the below steps on the build agents
• Go to Start->Programs->Microsoft Team Foundation Server 2010/ 2012 ->Team Foundation Administration Console
• Select a build agent and click Properties
• Change the working directory from to $(SystemDrive) to D:, E: etc depending upon the free disk drive

Explanation

TFS Service account requires the follwoing permissions on TFS - Share Point DBs

The treepath field type supports only system.areapath and system.iterationpath and cannot be used for the custom fields. It’s a limitation

Explanation

Any time a pending change is made to an item, the file types list is checked to see if the extension requires automatic locking at checkout. The idea behind automatic locking is that some file types (images, for example) are hard to merge, and that it may be beneficial to keep two people from working on the same item at the same time.

Workaround

The list of file extensions is configurable through the Team Explorer by right-clicking the root (server) node and selecting Team Foundation Server Settings → Source Control File Types.

To disable automatic locking by file type, you can find the file extension you're interested in, click Edit... and check the box for "Enable file merging and multiple checkout."

Explanation
The reason is that the build agent account doesn't have permission on your source tree to checkin other user's changes

Solution
You need to right click on the source tee in Source Control Explorer. Then click Properties and go to Security tab. You can then select the corresponding user of group and check the Allow checkbox for Check in other user’s changes.