I had the exact same issue. My hackintosh was working fine for a while. Moved my setup a few feet to a different desk. Started experiencing the same issues you were having. I tried new ram, cables, monitors, flash drivers + installers (different versions), new/old kext, etc. Everything would be fine after the initial install then after an hour OR a reboot I would experience your exact same issue. I purchased a GT 710 since it appeared to be graphics related (even though HD4000 was recognized it acted as if it was not) and everything has been working perfectly the past day or so.