Unfortunately it is a known issue from one of the last updates.
I still have some issues.
Try uninstalling Flash player and reinstalling the beta version of flash player or the most recent version. The steps to uninstall can be found at the bottom of the page here:
http://labs.adobe.com/downloads/flas...10_square.html
The beta version of Flash is on the top half of the page. You want the version that says for 64-bit Mac OSX
I use Safari and have intermittent issues with the new Flash Player. The beta seems to work a little better than the other version. At least now when I have problems, I just get a pop-up window with an error and I can click Dismiss All and it goes away.
You can also search the Apple support forums. There has been lots of discussion about it.