I've tried your advice and hope it works. There is also something worth mentioning, though it is a bit confusing. I had gone without a freeze for nearly a week of constant use, until... Until I did a partial update, which included a new addition of firefox. Suddenly, the system was freezing every hour or so. While I know it is not firefox, I am now suspicious that there is, however, something about firefox which may bring out the bug. But it may have been other components of the update -- I don't know. But the update certainly had a negative effect.
Updated to 3.4.6-generic and had another freeze. However, and interestingly, it was slightly different this time. I was able to perform a half-successful ctrl-alt-backspace, but I still had to hard-reboot. Overall, 3.4.6 is pretty solid in general and unlike 3.3.6, it uses less resources, for example, sensors was showing a constant 56Celsius, while in 3.4.6 sensors shows 46-48Celsius -- a big difference. Also, an interesting - but unrelated - link about nvidia privilege-escalation: http://linux.slashdot.org/story/12/08/0 ... ation-hole
Still no freezes and system seems generally improved. I can confidently call this issue "SOLVED" for myself.
Switched to 3.3.6-030306-generic and have experienced no freezes yet. Got some errors with upgrade along the way but overcame them and all went well enough. So, thanks again ingeva, I think this may have worked. I guess I should have tried it sooner.