problem with memory

i am running g.skill ddr2 1066 pi addition gaming memory. my mother board is a MSI p45 platinum series socket 775 with an Intel core 2 duo 45nm 3.0ghz processor water cooled and every time i put the memory at 1066 i get instability and after a while the computer crashes and resets. now the bios for this mobo is easy to use and overclocks the memory to where it suppose to be with out any problems. had to fix the timing for the memory but other than that i cant see why it wont stay at 1066; works fine @ 800. if anyone has some help to fix this problem i would sure appreciate it.