I have a problem with my firewall and through reading figured out that perhaps there was a rootkit problem. I found a post on this website with a similar problem and followed steps. I ran Roguekiller. This got rid of some threats but the firewall problem still persisted. The next recommendation was Combofix. I ran that and the program ran fine for a while then the computer went mad, the blue Combofix window as flashing repeatedly and the CPU was at 100%. I couldn't stop what was happening so held down the power button to shut the machine down and rebooted the computer. Everything looked ok but then certain application wouldn't open. For example Google Chrome. A message flashed up to say that something had been marked on the registry key for deletion and that an item had been moved. I managed to restore the system using a restore point. Now everything seems to be working ok. How do I know if everything is ok or not. Since running Combofix I then discovered all the posts that say never run this unless you are a professional so feel pretty stupid and am worried that I have done some serious harm although as I say everything seems to be run ok. The firewall still doesn't work though. Many thanks.