I'm running Windows 7 64-bit with Flash 11.3.300.257 and IE9 64 bit. Videos on some web sites simply won't play in Flash - the window shows as black - while others work ok. Flash videos on comedycentral.com won't play at all. Although I was able to watch the live video stream of Wimbledon on espn.com, video clips on the site won't play. However, some sites, such as hulu.com, work fine.
I've tried re-installing Flash, running IE9 32-bit, running Chrome instead of IE9, deleting the cache, disabling hardware acceleration, updating my Radeon HD 4250 display driver to the lastest version, and ensuring local storage is enabled for the web sites.
I've run out of ideas. Can anyone help?
I also had this problem and managed to fix it by doing the following, found at http://forums.adobe.com/thread/889577?tstart=0:
Perhaps it will help you as well.