hmm... not totally sure. I'm assuming you've updated to the latest flash player and tried re-installing it etc..
I'm on a Mac so this might not help but I sometimes have trouble using Flash features when other extensions or control panels are loaded. For instance, when I have my MP3 converter loaded (N2MP3), I can't use the Flash upload feature and have to use conflict catcher to restart without it.

Maybe somebody else more familiar with Windows knows?