Upgraded the home Windows 7 laptop with Firefox 4 last night and got a nasty surprise when I went to access some YouTube video: system kept freezing up in advance of a full out browser crash.
Initially I blamed Mozilla, but after getting the same result after a downgrade I took to the Google and discovered many others were having the same problem. Turns out the root cause was incompatibilities between the latest version of Adobe Flash (10.2.x) and some older video drivers. Taking my cue from this, I went up to the AMD/ATI download area and grabbed the latest driver for the laptop’s video subsystem. An install and reboot later all was well again (at least after I re-activated the Menu toolbar that’s turned off by default in Firefox 4, undoubtedly due to some misplaced Chrome-envy on the part of the Mozilla UI team — almost as great an annoyance to me as the Gnome team’s attempts to banish Terminal from my desktop).
Man, I really hate Flash.