Memory crashing?

First off, i wanted to see how high i could get my FSB. I got it at 155mhz without Windows crashing, good. I then went into my bios and put it at 160mhz. Posted but got an error before going into Windows. I then put it at 157mhz, booted into windows but as soon as the screen appeared it rebooted on its own. Now im back at 133mhz (266mhz DDR) because im happy with it, although when i get my new Enermax psu, im gonna overclock the hell out of this machine I did do this test with all settings to max. Could it be that my memory settings were too agressive? or is it the memory that chickened out? At 155mhz i got scores of 678/820 in Sandra

BTW : I run WindowsXP, see sig for the other stuff.

It's more than likely the memory m8. Try less agressive settings, and make sure you've upped the volts a bit too. 160 is a bit high for 2100 but you might make it.