I have installed Firefox 4 and I quite like it. Bar one thing. Every couple of hours it randomly stops working. It doesn't become unresponsive or crash but, using the example of tabs, if I click on them it changes its look to what it ought to be when the mouse is hovering over it.

But noting else works. I can't click, I can't type and I can't quit and it gets very frustrating. I have to force quit and reopen, which is a pain because I have about 8 songs on YouTube open that I've been listening to and I have to go through and pause them all again each time I reopen Firefox.