I installed Adobe products today (Photoshop, Lightroom), and Adobe Media Player was included. I don't know that it was cause / effect, but I was on YouTube shortly thereafter and got only black screens. (Firefox5 and Opera12, 100% non-functional. Very buggy in IE9.)
Research indicated that this condition happens to a lot of people, but for many reasons, and I was unable to narrow done causes or solutions. I downloaded and overinstalled the latest version of Flash (though my version should have been fully current). That fixed the problem and YouTube videos played fine afterward.
However, I noticed that the installer was missing.? I download all installers to a specific directory so it was easily noticed.
Is the Flash installer supposed to self delete? If so, why? If so, it would be nice to be advised.
(Didn't care for the default selected McAfee garbageware on the dowload page. Would have been very easy to miss. The 'download' button is designed to bring the eye right past the garbageware.)