I would add, that it happened to me with the final version as well! Clicked Try Ubuntu in the Live CD menu, then for about 5 minutes, nothing happened, although the system was / alive / , so the cursor was moving and all desktop elements were clickable. I had to click the red cross to exit, then clicked OK, finally the desktop was shown, but with the bug reporting tool showing an ubiquity crash.
I would add, that it happened to me with the final version as well! Clicked Try Ubuntu in the Live CD menu, then for about 5 minutes, nothing happened, although the system was / alive / , so the cursor was moving and all desktop elements were clickable. I had to click the red cross to exit, then clicked OK, finally the desktop was shown, but with the bug reporting tool showing an ubiquity crash.