I'm not sure if this is necessarily a Ubuntu question, but I've only had the problem since I installed 12.10. When I turn my computer on, the BIOS screen comes up as usual and... nothing else. When I press any key, I hear a loud beep and there's no response. I've tried looking for similar problems, but in most cases people are at least able to interact with their BIOS even if their OS doesn't load. It seems as though it's just completely freezing as soon as I turn it on.