No, getting stuck is not normal at all. How long is it stuck? Is there any activity evident on the screen? Is the drive light blinking on the PC? If it has truly stalled, and canceling the Tune-up and restarting it does not resolve the issue, please contact support.
How to reach support (FAQ) - http://social.microsoft.com/Forums/en-US/onecareinstallandactivate/thread/30400b52-7f26-4ba0-bc18-17e305329d90
-steve
Microsoft MVP Windows Live / Windows Live OneCare, Live Mesh, & MS Security Essentials Forums Moderator