Can't test this until tomorrow but here is what I hear:
This happens because of a security miscommunication between Microsoft and Adobe.
It can be remedied in a number of ways depending on what makes you and your system most happy.
Option 1: Put www.jonja.net
in your trusted sites
Option 2: Lower your internet security to Medium for the Internet zone.
Option 3: [Preferred] Download the FULL install for the latest version of Adobe Flash
Do NOT use the net installer or auto updater. Due the security issue it wont be able to run. Close all IE windows.
Update Flash and you will once again be able to game with us.
I'll verify all this and we'll put a note on the arcade page if it seems to do the trick.