casper what haas changed with the system? If nothing has changed, how old is the hard drive? I could be memory as everyone is stating but in the last 8 years I have only seen one bad memory module. And once ram was working it seem to just work. It may slao be a bad sector onthe hard drive which is causing a boot failure. If there is a critical file localed in that sector it could just go south. Reloading the OS will/should correct issues with booting. Are you able to boot the system for a boot disk or with a bootable cd-rom. if you are that would lead me to believe it is not a memory issue. since you are starting the boot process again it is something that is loading (or not loading, bad sector) that is causing it to stop