NVIDIA "Threaded Optimization" option causes major freezing!

(If you're lazy read from the bold point below)

Hi all,

I'm not really sure where to start so I'll try my best to fill you all in..

I've been having troubles with HDD's since.. forever. I thought my motherboard was killing them (it also had a few other issues like not finding my PS2 mouse etc.) so a while ago I bought a brand new XFX750a motherboard.

A couple months went past without any problems, but then only a few days ago my computer melted and 3 of my 5 drives failed with bad blocks, clusters.. all sorts (what the 8 drives had done before hand that I've had to replace). I managed to save a couple just with formatting and defragging, but I've bought a new 1100W power supply as I suspect my old 650W was causing troubles, being the only component that has stayed the same while I was getting all these troubles with drives. I've also bought a brand new WD 640GB drive as my primary as I don't want to put important data on drives which have failed on me once already.

( LAZY PEOPLE START HERE! )

So of course.. I've re-installed XP, everything going smoothly until I hit games..

I first installed PKR as I do love my poker, but as soon as I got to any 3D part of the program my computer would freeze up and jump uncontrollably. I re-installed.. same again. I then thought okay, maybe PKR is messing around? So I installed Crysis, but the same was happening with that.

This freezing is almost like what happeneds before BSOD where you just hear a loud hum before everything turns blue, but it only lasts a few seconds and then jumps to the next frame or two and then freezes again.

I searched around for a while and came across a thread (not on here) which said to disable the 'Threaded Optimization' option in NVIDIA's control panel. I did so, and the problem is 'solved'. Thing is.. Threaded Optimization has always worked with this computer before, and I wonder now what is causing me troubles.

Does turning this feature off mean my games don't use my dual core properly or only a single core?

Any help on this would be very much appreciated.

Thanks in advance,
Ace.