I've got same problem only with MSI H55M-P31 motherboard.I had also to demount 1 slot of RAM for installing a 64bit version of Windows 7 and after all was done,and I mean all god damn possible updates and stuff,I turned off power,putted back RAM and hit start button.....blue screen filled with errors..Both RAMS are Kingston DDR3 1.3GHz 2GB,and both are OK...So what the hell is problem?