I had a problem with random reeboots after the first FW update last year, but after I overclocked my phone the random reboots has gone away I do not surgest you to OC your phone, but it somehow fixed it for me (I've got two in one, a faster phone and no random reboots )... I've had one reboot after I OC'ed my phone and that could be anything and before i had 3-5 a week... IMO i don't think a reflash would help, you would just flash the same kernel on to it again. I think the problem is in the stock kernel cause mine got fixed with Titans enhanced kernel for oc'ing and thats the only thing i've flashed on my N900 (the kernel). I'm now running a kernel from dj_steve with patces from Titan so i can dualboot maemo/nitdroid and OC .