After upgraging Firefox to version 13.0.1 it hangs on any(?) web-site with Flash. When flash is loading the browser hangs for a minute or so. When video comes to the visible area of the browser, it hangs forever. No memory growing, no processor used, no (not responding) is displayed. After manually killing process plugin-container it gets restarted immediately. After some quite long time it may report that some internal script is not responding (script is related to the ieTab plugin). Disabling plugin doesn't help, it complains about another plugin. All my colleagues have the same problem (we have similar configuration). Most of them have already gave up with Firefox and moved to Google Chrome, as the former became unusable. If the problem is not fixed soon, this can be the exodus of the whole large office.