I've just updated to beta version 10,1,51,95 (Beta 3) and I no longer have trouble going to full screen or changing the resolution like before. My picture even seems better, although I don't know why that would be.
For windows Firefox browser, I downloaded the active-x and the plug in and like Sclithroe says use the Adobe uninstaller.
http://labs.wip3.adobe.com/downloads/flashplayer10.html