About two years ago, after a couple times of having to reinstall windows a few times on my laptop a three year old (now) one by now. All of a sudden after working pretty well before that the computer does not even boot completely. The operating system i believe is Windows XP home edition and i have been trying to install Window XP professional edition that my grandparents have given me as a present. However, now the computer boots up for a while until it gets to a black screen which i believe is when the computer begins to warm up. However, during that time it begins to check all the hardware and everything but mysteriously it just turns off automatically without any reason before i can even get to the place where you long on. I have been looking around at different website and due to their many recommendations i was told to take out and reconnect the motherboard and hard drive. If that did not work i was supposed to buy a new one. I was just wondering how to go about fixing it. The fan works okay but that could be the problem because i always used to leave it on at night and played games on it for hours. Most of the computer guys that came to check it out suggest a virus and reinstalling the Windows again. However, when i insert the cd it says that their is no floppy in the drive and to please make sure the hardrive is connected and turned on but i assume it is. Is their anyway about reinstalling Windows XP and it actually working? Will i be able to use Windows Professional on a computer that had windows xp home before or are they incompatible? The laptop is a Compaq Presario 2100 and i did not tweak in any way except routine reinstallation of Windows XP. Therefore all the specifications are the same as the factory made. Thank you for reading this whole thing and thank you even more for answering. In addition when i start up the computer in safe mode it flashes to the compaq screen and then goes black for a while before it gets to the windows xp thing and restarts again. I tried reprogram to the last settings that worked and it wasn't any better. I ran the diagnostic and it says test status #1- 07 fail. What does that mean.