I constantly need to move the windows of Firefox to get the page to visually refresh (like to unpin the window from the top).
The problem: I'm on a page, I want to go anywhere else, or I click on a link. The screen stays on the same page until I move the browser window.
The browser is not freezing because the page is already loaded, it's only a display problem.
It happens like 15 times a day. The only thing in common with the iMac and Macbook Pro (on which the problem happens): They both have Firebug installed. I tested the FF5 beta before upgrading to 5 stable (and up to date) on the two Macs too.
PS: My colleague has the exact same problem. (It's been happening since 2 months approx.)