I would recommend reinstalling/updating Comodo Internet Security (CIS) to the newest version by following the steps below whether you've had problems or not. This will likely avoid most problems you could otherwise encounter.
Before you continue with any of the following advice make a system restore point. This way if something goes wrong, which although unlikely is possible, you can easily recover.
1. Uninstall Comodo Internet Security/Comodo Firewall (CIS/CF)
If you are running a 32 bit operating system I would recommend that you uninstall CIS with Revo Uninstaller Free, which can be downloaded from this page
. Note that it will not work for those running a 64 bit operating system. Revo will make sure that almost every file from your previous version was removed before you install the new version. Just start Revo and wait until Comodo Internet Security (or Firewall/antivirus, depending on which variation you have installed) is listed. Note that for x64 machines Revo will not locate CIS. You should go to the next paragraph for instructions on what to do. Otherwise, in Revo, choose to uninstall CIS using the moderate search option. Revo will first uninstall it normally using the builit-in CIS uninstaller. When the CIS uninstaller finishes it will prompt you to reboot, but select no and let Revo complete its process. It will then search for, and find, most files/entries that are left over. I would recommend that you delete all. After this restart your system.
If you are running a 64 bit operating system you should uninstall CIS through the "add/remove programs" in the control panel. Just let it finish and, when it prompts, allow it to restart your system.
2. What to Do If CIS/CF Was Unable To Uninstall Correctly
If Comodo failed to uninstall correctly, but is still running, you need to go into the configuration and disable Defense+. Then continue on to the next step. If you are not able to access this option then continue to the next step anyway.
3. Clean Up Any Remnants Left of CIS/CF
Once CIS/CF is uninstalled, or at least removed as much as possible, you should restart the computer into Safe Mode with networking. Instructions for how to do that can be found here
Then run the Uninstaller Tool for CIS (note that all uninstallers for CIS will also be able to uninstall Comodo Firewall), which can be downloaded from this page
(although I would advise not running it on computers with Windows 8, as problems have been reported
). Once you're done using that program to uninstall Comodo Internet Security you can use another removal tool. This one should be safe for Windows 8. This second removal tool can be downloaded from this link
. After opening this application first run step 1, which attempts to kill any remaining proceses from Comodo Internet Security. Then, once that is done, you should run step 2, which removes any remaining files and folders. Note that there are other options provided, but that I would strongly advise that you do not use them. Only the first two are meant to remove Comodo Internet Security. The rest are for system maintenance and sometimes may cause serious problems with your computer if run.
After both have been run you should restart your computer.
4.Clean Any Remnants Left From Former Security Products
If you ever had a different security program installed before you tried uninstalling CIS, then part of the problem could be due to interference from their leftover files. To ensure that this will not cause a problem please run the removal tool for each of those security programs that you used to have installed. A list of uninstallers for common antivirus software, can be found on this page
. Please select the ones for any security programs you previously had installed and run them.
5. Now Install Comodo Internet Security
Download the latest version of Comodo Internet Security from this page
and install it. Everything should now hopefully go flawlessly and you will have the latest version installed on your computer. Once it's installed you may want to follow my guide about How to Install Comodo Firewall
for advice on how to configure it.
What To Do If The Above Steps Did Not Solve Your Problem
6. Run A Registry Cleaner
You can also try cleaning your computer with a registry cleaner. This may help fix some problems. Whichever registry cleaner you choose, you should make a full registry backup before removing anything. Once it's finished cleaning you should restart your computer. After running the registry clean you should go back to the beginning of this topic and follow the steps to remove any remaining components.
7. Manually Remove Leftover Drivers
To locate any Comodo drivers which may still be left on the computer go to the windows device manager. For help in how to open this please see this page
. Then go to view and make sure that the option to Show Hidden Devices is enabled. Then look under Non-Plug and Play Drivers for drivers called Comodo Internet Security Firewall Driver or Comodo Internet Security Helper Driver. If either of these still remains right click on it and select uninstall. Note that this should only be attempted if every other attempt to uninstall it, and remove all relevant files, has proved insufficient. After removing these you should then go back to the beginning of this topic and follow the steps to remove any remaining components.
8. Ask For Assistance In The Help Section Of The Comodo Forums
If none of these methods work then please start your own topic in the Install / Setup / Configuration Help - CIS
section of the Comodo forums. People will examine your specific case and try to help you figure out what's interfering with the installation. Just make sure you supply the information suggested in this post
. Also, please note which of the methods discussed above you have already tried and what the results were.