Security Shield blocked by COMODO

Some application has managed to sneak on to this computer (Secuity Shield). COMODO blocked it but I can’t uninstall it. It is keeping me from running spybot and won’t let me into most of my programs. How do I get rid of it? It keeps poping up with a message that serious viruses are on my computer and if you try to remove them, the message tells you to pay for it. Comodo does a scan and the log says no viruses are found. Help!

Follow What to do if you’re infected - eXPerience Rev.3 for now and let us know how things go.