I currently run 1 piece of 512MB PC133 SDRAM. My motherboard is an ASRock K7VM2.

I recently bought another piece of the same ram and installed it into the 2nd slot. I've checked my manual and can see that it will handle 2 x 512. When I started the computer again, I noticed in the startup screen that it recognised the additional ram. The windows loading screen pops up, then the computer spontaneously restarts. Now the additional ram isn't being recognised, it only reads 512. The computer just continues to restart itself, windows never loads. I've tried swapping the slots, which didn't work, but running each pieve of RAM individually does, which tells me it isn't a problem with the ram.

Any ideas?