P4PE memory timings

I think my P4PE may be a bit flakey. I am running a 2.4b C-1 with 512 mb of corsair PC 3500 XMS (two sticks) and a ATI 9700 AIW. Anytime I try to up the fsb it says CPU failed due to overclocking. And if I run the memory in anything but 266 it says the same not memory test fail. I have also tries to use different memory with no sucess. Anyone with any insight would be appreciated.

hmm I have mine set to 355 at 2-2-2-5-T1
is there a CPU speed check on?