A few months ago I tinkered with my RAM and as a result I'm only running half the amount of RAM I was. I have an MSI K8N Neo Platinum with two sticks of Crucial DDR400 512 MB, and three RAM slots on the motherboard. After tinkering I turned on my computer and the mobo beeped with no other response, and after some experimentation I discovered that the only RAM combination that allowed my computer to boot into Windows was one stick of RAM (either one) in the first slot. Only one other combination brought me close, and that was one stick in the first slot and another in the third. This allowed my computer to POST, and when looking in the BIOS it verified that I had a gigabyte of memory installed. However, it hangs whenever I get to the Windows loading screen (the loading bar). I don't know how to run memtest but im guessing that I'm going to be asked to. Any other suggestions?