Wildcat,
What are your machine specs, operating system, peripherals, etc?
I gave up on Norton many moons ago - it is a pretty big resource hog, but I don't think it's as bad as it used to be. I just built a couple of new machines this last year and did a bit of research on anti-virus. Tom's Hardware guide and others ranked Avira's Antivir as the best free antivirus software, and that's what am using. It's already caught more crap than AVG or Norton ever did for me.
Did you try uninstalling Malware Byte's and reinstalling? There are some malware that block it and other AV programs from running. From the limited info, it seems like you have some nasty malware on your maching. Open up your Task Manager/Processes and look for any weird programs running. Most of the time, if you see an unknown process running, you can Google it and get some additional info on it. If it's Malware, it's usually flagged.
Good Luck!
Cheese