OK, I've had this problem since last few months. I'm using Windows 7 Ultimate and I have a lot of browsers installed on my system (Opera, Firefox, IE9 beta, Safari, Chrome). But whenever I start any of these browsers (except Firefox), my taskbar freezes completely. I cannot access anything on the taskbar including the start button. After pressing Ctrl+Alt+Del, I select 'Start Task Manager', but that also freezes. Its as if anything related to explorer.exe freezes. The system only comes back to normal when I close the browser window. Suprisingly, Firefox is the only browser which works perfectly without freezing the taskbar. I've Firefox 3.6 as well as Firefox 4.0b6 installed and both work without a problem. Any ideas?