I have a very annoying Trojan Horse problem. Please advise...Thanks.?

I don't exactly know how the Trojans came into my desktop, but it happened. Everytime I scan with Ad-Aware, my computer hangs, and I have to pull the plug, and turn it on again. I also used Symantec Antivirus, and cleaned whatever risks it found. But every minute, i get a pop-up that says there was risk, and it was quarantined. If I don't close the pop-up, more and more risks show up in the window, and are all supposedly quarantined. The list just grows and grows, and if I close it, it will just reappear later, starting again. Also, I keep getting pop-ups from internet explorer, on random things. I only use firefox, but an IE pop-up shows up. I also get messages like error has been detected. Would like to install drive cleaner, or system doctor? I know they are all viruses, so I don't download, but they keep coming frequently. Please help if ou can.

I have a very annoying Trojan Horse problem. Please advise...Thanks.?norton internet security

One of the first things to do when you suspect malware is DISABLE System Restore.

If enabled, this allows malware to hide in the computer and re-install itself.

So, to disable it, RIGHT-click on "My Computer." Select "Properties" then under the 'System Restore' tab, check 'Turn off system restore' IF not already checked.