I was working on a PC and the firewall would not start it had been infected by malware, I had cleaned it up but it still wouldn’t start. After some Bing’ing 🙂 I came across this utility of Eset.
http://kb.eset.com/library/ESET/KB%20Team%20Only/Malware/ServicesRepair.exe
Download it and ran it and all started working as you would expect. 🙂