I don't know if these issues were related, but recently I have been having
issue with Speed Download 5 (download manager app for mac). I decided to
uninstall it because of other problems and was able to get Flash Builder to
work after re-downloading fb4 and uninstall and reinstalling the new
Bare in mind, this may not be related, but I thought it was worth mentioning
in the event that you also use the app.
... my problem is the same message as above but on Windows XP 64-bit, FB4 plugin and standalone have the same issue... I tried to install the plugin version when it was first available with Aptana but no dice because it was on eclipse 3.2, so I uninstalled it. Now Aptana is using ganymede/3.4 so I'm able to install FB4 beta without a hitch but the trial license is bugging out. I've installed, uninstalled, restarted, used the license manager repair tool, double checked the permissions of the Application and Settings folders etc... Stumped.
When I installed Flash Builder, it caused a registry conflict with CS4, which required that I uinstall all my Adobe software and run registry fixes (call customer support for this part). Once I reinstalled Flash Builder, I had the same problem you're describing now. From there, I had to wait until this site page was launched:
Now, everything works fine.