who told you to run two antivirus softwares at the same time? They never work that way.
And your selection of antivirus, esp. Norton , thats the worst piece of junk known to mankind.
Download malwarebytes, quick scan and remove the threats. Then full scan afterwards if you've time.
Run AVG 30 day trial to take your cleaning to next level. Do yourself a favor get those junks out of your system, I mean NORTON.
And, MSE at times is sluggish as hell. When it can't remove the threat, it freezes your PC, not really, but eats up your resources trying to remove it. I've core i7 intel 2nd gen CPU clocked at 3GHz with 8 GB DDR3 RAM and believe me, MSE did that to me couple of time, slowed my system. I had to bruteforce kill to bring it back to life.
So, long story short, it's not that virus which is not letting it complete, it's your two antivirus engine probably conflicting and not letting it done. Virus striken PCs normally don't let you change your administrative password, let alone running your antivirus softwares.