Quicktime made itself the default plugin for Flash, which causes flash sites not to work. What can I do to change this?
To remedy this problem, open Quicktime and select: Edit -> Preferences -> Quicktime Preferences. In the preferences window, click on the MIME settings button. Then, select Miscellaneous and uncheck Flash File. After this is done, (re)install the Flash plugin and everything should work. Having the Quicktime plugin for Mozilla is actually quite useful, especially for embedded audio (.wav, .mp3) and video (.mpg). You just need to tell it what it shouldn’t handle.