3.9 update made me do a system restore. Help!

Downloaded and installed COMODO Internet Security 3.9.76924.507. I had version 3.5 because had problems with spy sweeper and previous update. Uninstalled 3.5 with Revo Uninstaller and installed new version. After restarting the computer there was an error message that comodo could not be loaded. I tried to uninstall it and it would not uninstall and said that comodo is running. It blocked my internet and the internet hanged. Had to do a system restore and go back to 3.5.
Anyone have any ideas what went wrong?

I am not sure what went wrong. Try uninstalling v3.5 and follow this guide to get rid off all remnants of CIS: https://forums.comodo.com/help_for_v3/comprehensive_instructions_for_completely_removing_comodo_firewall_pro_3_info-t17220.0.html . Forget about the legacy keys as they are a lot of work to get rid off.