Thank you for giving the SPECS , stating the problem clearly and the steps you have already tried to troubleshoot your Random Freeze problem with win 7 Bit 64 Build 7077. I have tried it in a different hardwae environment but luckily has not encountered the problem you are having.
As you might already know the most important causes of "random freeze" is still mostly hardware related and often Thermal , Memory ( RAM and Virtual) and Driver related the last one often from Video card.
Overheat of Processor and other devices inside the Chassis can cause the computer to behave erratically and it may become unresponsive to commands using the mouse or Keyboard which we call "freezeup or "lockup". In some instances computer can go into sudden BSOD . Overheat of the CPU from lack of proper thermal grease, clogged vents of the Cooling System (heatsink & fan assembly) from accumulated dust and moisture and intermittent or complete failure of Case fan or even CPU fan that is in its last leg by spinning against the resistance of caked in dust, case vents butting against the wall or a computer tower neatly tucked inside with all the cables in a computer cabinet with very little ventilatory openings, Hard drives coverd by criss crossing wires and cables are all common causes for premature computer death often preceded by such unresponsive spells. Decreased amount of RAM or increased demad for it from multiple processes especially Video/Multimedia and similarly low virtaul memory from decreased free HDD space occurs usually a little more predictably after some use. Never forget Virus and Malware for unusual computer behavior even if you think you have an Antivirus as many trojans craetic artists are one step ahead of Antivirus vendors. In a Beta OS lack of proper drivers can cause BSOD but not freezeup in the usual sense of the word.
My personal suggestion is to rule out overheat and then look for other causes.