PC Start up Problem

[kayvaanshrike]

I replaced one of my 256mb 400mhz ram with a 1gb 400mhz one. It was working great, however, when I turned my pc on it loads up then after the windows blue bar thing has loaded it does a blue screen for less 1second (I don't even have time to read what it says only a few words at the top left hand corner) then reboots and then the menu comes up with start windows normally etc( My keyboard does not work at this stage, it did at first well kind of every key I press the num lock light just lights up). I took the 1gb out and put the 256 back in, still the same problem. I even took just the 256 and left the other one in. I have reached my limit I don't know what else I can do.