Strange stability problem

e4300 at 2.93ghz 1.35v
GEIL 6400 at 800mhz 5-5-5-15
ecs 650i

I am overclocking my e4300 and it runs orthos fine overnight. It completes the OCCT 30 min test with no problems. Memtest86+ says everything is good. Temps are always under 50c

Now comes the strange part. While overclocked i experience seemingly random lockups of XP. Whether i am just surfing the net or gaming or extracting files. It is just random.

I have found that one program called ProShow(used to make pictures on dvds) always locks up at the same time with this program when i am overclocked.

It runs fine when i am in the range of 1.8-2.1 ghz but any overclocking beyond that locks the computer at the same spot using ProShow.

Am i missing something because i was feeling pretty good about myself with this overclock after orthos and occt completed since i have no experience.

Great news for me anyway. I had been running and passing memtest86+ off the UBCD. It always told me my memory was fine. so i ended up running plain memtest86 and it came back to tell me i had errors. I pulled out one of my sticks of memory and found that i have a bad memory stick.

With that stick out both memtest's passed and everything runs fine.