I wouldn't recomend OC'ing your phone either, for me it just 'cured' my phone from random reboots, it's just an information too consider, an obtion for getting rid off the random reboots (for some people it works) If it don't just flash your rootfs and your back to normal. Further more you don't have to use the OC'ing you can run your cpu at 600 mhz, no cpu overheat.
I don't think Nokia can fix it, if one choose to send it back, cause it's in the stock 'kernel' there's a problem. I got it from a ota update of the FW, not from some app or fidling with my N900 in xterm and poeple say they've flashed there phones and still the problem is there.