Firewall refuses to uninstall

(:AGY)Uninstalled the free Personal Firewall from XP Prof after it got corrupted. Used the Windows control panel uninstaller. Still had problems. Then removed all the bits in Program Files and the Registry (all references to Comodo firewall) and everywhere else that is visible to me. When I try to re-install a new one from Comodo it blocks me from downloading and re-installing it. 2Comodo Firewall is already installed" “Do you wish to uninstall it?” (YES I DO) My email Inbox is littered with new Activation Codes each time I re-apply. Any ideas Please… :THNK