I heard good things about COMODO and needed a anti virus. I downloaded, ran a scan and the next time i restarted it, I now have a black screen that is absolutely unresponsive. Can anyone provide a suggestion?

Did you install the Comodo AV or the Comodo Internet Security? What version did you install or where did you download it from? Did it find viruses that it asked to remove?

Can you boot into Windows Safe Mode? When you can please make sure that there are no left overs of previously uninstalled security programs around. Not all uninstallers do a proper job. Left over applications, drivers or services can cause all sort of “interesting effects”.

Try using removal tools for those programs to remove them. Here is a list of removal tools for common av programs: ESET Knowledgebase .

Then run this clean up tool for CIS.

Now we have a clean slate. Now you can try installing CIS again. Hopefully it will now work.