Computer Issues when running AV

[Wonderboy]

Hey, recently my computer has been acting up, completely locking up/freezing and failing to perform AV scans without locking up and requiring a restart. My computer runs legit, up to date Avast AV, Malwarebytes, Spybot S&D and used to have Ad-Aware too. A few weeks ago the system started to freeze and lock up, firefox and itunes could be the only things open and it would just freeze. My instincts said malware so I attempted to run Avast, MWB, Ad-aware, MSE, Spybot S&D and almost none made it through without locking up. I said "well played malware" and went into safe mode, ran things again one at a time, locked up again. Eventually I uninstalled Ad-aware (imo rather buggy software), assumed it was a conflict issue and hoped it would resolve it. Nope. Eventually over a few days and many attempts one by one I got clean bills of health from Avast, Malwarebytes, MSE and Spybot (i did get a few cookies and random non-serious stuff which I removed anyway). So given that I also use tune-up utilities to defrag both the registry and HDDs, clean all the other crap that builds up over time I thought I would reach out and see if any of the experts on MMO-C had a clue whats going on. I know the easy answer is backup and reinstall windows but for some weird reasons that my Win7 version was a special upgrade offer, went to an uni email i don't use and other stuff, it would be a right pain to do so (especially as I intend to build a new one in say 2 months). System is a dual core 4 gig ram system that shouldn't struggle like this. Also the cores go dead when it locks (from 50% each scanning to 0% when it freezes). Is there anything else I can try?

TL;DR
- System freezing running AV and locks up randomly
- No viruses/malware
- System optimised
- Why does it hate me?

[lockblock]

its very possible you don't have a virus but possibly a dying hdd
does it freeze when accessing those particular files that cause the av to freeze up?

[Raid]

External Hardrive transfer important Infomation,
System Restore A.k.a Format your HDD

[Wonderboy]

It froze twice on the exact same file, i removed the file and it went through but other times/other programs are seemingly random. Have also done a full check and repaired all bad sectors on the HDD.

External Hardrive transfer important Infomation,
System Restore A.k.a Format your HDD

As mentioned in my post i'm aware of this but would rather avoid it if possible for the reasons listed earlier.