If you are experiencing problems with your Beta 2 help, you may need to repair it, especially if you had a prior tech preview installed.
The Help 3 team blogs tells you how to fix it:
http://blogs.msdn.com/help3team/archive/2009/10/21/how-to-repair-a-help-viewer-help-3-beta-2-installation.aspx
Good luck!
AprilR