System freezes completely unpredictably 2 or 3 times within an hour or less (no mouse, no keyboard input accepted), until a hard reset each time. I then shut down and use a second desktop system with Ubuntu 14.04 that never quits (it has built-in Radeon graphics). The Ubuntu system is AMD 4200 64x2, with 4GB ram and 500GB HD--a slower system, but more reliable--fully up to date, too. Neither system is OC'd.
I have run ClamAV via TK and get 53 threats on first system, none of which can I quarantine or delete! I had run Clam previously and was able to quarantine uncovered threats. I am not sure whether these 53 recently uncovered threats were the ones I had previously quarantined, but if so, I should have been able to delete them--I believe.
I have seen others report similar issues to the one I have reported above. A few seem to think the Nvidia graphics 340 update is at fault--others do not. I do not know what to think, but this is very frustrating on my primary system.