|You committed the 2 biggest mistakes:|
"I was running Mcafee but found it disabled and would not enable. I then installed Symantec but it will not update virus definitions."
You have to use the uninstallers from their websites to remove all registry items from your PC. Those are the 2 biggest resource hogs online.
I would suggest unloading them and then running:
1- Trojan Remover
2- Hitman Pro
They should remove the problems for you.
Then get a good anti-virus like Avast which will work great for you.
You can uninstall those 2 after they run clean as they are just 30 day trials.
Some HELP in posting on Computing.net plus free progs and instructions Cheers