I have just finished spending DAYS trying to solve a problem I was having re-installing Internet Explorer 8 on a computer I have at work. It turned out that the problem was that I had to completely UNINSTALL Comodo before I could get the re-install of IE8 to work. I'm just passing on the info here in case something similar happens to anyone else. First, the story, and then the bottom line. Here's what happened: I was trying to figure out why the computer was running slowly. The computer is a Dell Dimension 3000 with Windows XP Professional on it. It has a 2.79 GHz processor and 2 GB of RAM. A second computer at work is identical except it has 1.25 GB of RAM instead of 2 GB. But, the 2 GB RAM computer was running much slower than the other one. Both computers are stand alone individual computers and are not networked together or connected to any network. Both computers have virtually identical software with identical programs running at startup. Both computers have Microsoft System Essentials (MSE) and Comodo (firewall only) installed, and both have Carbonite backup running in the background. Both computers have QuickBooks 2009 running on them which requires IE8 in order to function correctly. After trying every type of malware and antivirus scan I could think of, including Super AntiSpyware, Malware Bytes AntiMalware, and MSE with nothing found, I started thinking that maybe the problem had something to do with an IE8 plug-in or add-on. So, I started messing around with those settings and managed to do something wrong that somehow caused IE8 to stop working. I eventually decided to uninstall and re-install IE8. I've been spending days trying to get the IE8 to re-install and work. I tried everything I could find on the Internet that was suggested -- all of the the fixes, all of the uninstall and re-install techniques, "clean boot" techniques, changing the "theme", etc. None of those things worked. Each time, the end result was that when I would re-install and then run IE8, I would at first get a modified IE8 screen (with the "File, Tools, etc." toolbar missing) and it would just say "connecting" but nothing would happen. After that, all it would do is flash an IE8 screen for 1/2 a second and then close. I tried having no programs such as Comodo, MSE, and Carbonite run on startup, and that didn't work. I tried uninstalling MSE because I couldn't figure out how to shut it down, and that didn't work. I tried closing ("exiting") Comodo, and that didn't work. Then finally I tried completely uninstalling Comodo -- and that solved the problem. BOTTOM LINE: Apparently, when re-installing IE8 on a computer that is running Windows XP Professional, one must completely UNINSTALL Comodo or the IE8 re-install will not work.