I have a similar problem. I open IE, or Firefox, and they work fine when I restart my computer, but that all of a sudden I try to open one of them and no window appears, but it appears in the processes portion of my task manager. I close both Firefox.exe's disregarding the "TERMINATE" warning, and they close fine, than I can reopen Firefox Safe Mode. But IE is different, I close all of them same way in the processec tab, but one will not close after I click end process, and it dosent show up in tasks. IT is using say 76,000 k of memory, but im fine since I have 2048M of ram. And ideas, cause i need to constantly be opening these windows.