I have a system with an ASUS P4B533, a 1.7 ghz celeron and 512 pc2100. I am running XP Pro. The system has been running great for a year. Then it locked up and I rebooted and since then it will get to the "black" windows XP screen with the three blue dots going across screen and I hear two clicks from what seems the motherboard or processor and the screen goes black and it stops booting. Or I will get to XP scandisk and it checks the whole hard drive and says it is ok then freezes. If I go to "safe Mode" it gets down to the AGP440 file and stops. I have replaced the Power Supply, Video Card and RAM. I have also disconnected everything else. I do get "Power on self test complete, computer now booting from operating system" from motherboard. Then when it gets to that black XP screen I hear the 2 clicks and it goes blank. Any ideas???