We have a known issue with performing builds on 64-bit machines with TFS. To overcome this simply modify your build definition and set your MSBuild Platform to x86 as show in the attached screenshot.
This will be fixed in our next major released currently scheduled for approximately May time frame.
the Telerik team
Registration for Q1 2011 What’s New Webinar Week is now open. Mark your calendar for the week starting March 21st and book your seat
for a walk through all the exciting stuff we ship with the new release!