I posted a message a couple of weeks ago re Microsoft not recognising the fact that I PC Guard Antivirus although I didn't seem to be having problems. I now wish I had taken notice of some kind soul who basically said "if it aint broke don't mend it"
I removed PC Guard and installed Mcafee, my computer got slower and slower, I removed Mcafee, reinstalled PCGuard and ran the scans, it found two Spyware threats and the Trojan killwin32. My computer is now back to normal. Panic over.