Hi Guys, To cut a long story short, I built a PC for a friend and it runs fine when it actually boots though! All the parts are compatible and brand new but from day one after setup the system has giving the following symptoms: Symtoms & Actions taken: * Inconsistent hangs during Windows XP splash screen: - 80% of the time system hangs on cold startup (after 6-12 hours switched off). - 20% of the time system boots on cold startup (very unpredictable). - If system hangs, Blue loading bar passes roughly 6-8 times before stopping dead. - HDD stops loading and reboot is the only option. - The system can hang anywhere from 2 to 8 times upon cold boot before working. - Usually the system will continue to reboot and run fine once Windows has loaded. - Sometimes it boots fine without a hitch from cold. * Computer can work fine for a day or two with absolutely no problems making it extremely hard to troubleshoot: - Booting into Safemode and Diagnostics mode with minimal drivers seemed to work. But due to the length of time in which the problem can stay dormant it proved Difficult to tell. - Attempted a fresh install of Windows 7 64bit on an empty HDD with nothing installed and problem still persisted [Indicating a possible hardware fault]. * Bootlogging the problem: - If system hangs, it hangs after loading the file "Mup.sys". - Google searches indicate that the file following "Mup.sys" is an AGP file. * Troubleshooting GPU: - Removed current GPU, Galaxy Low Power Geforce 9600 GT 512mb. - Replaced with Galaxy Geforce GTS 250 1GB. - System worked flawlessly for more than a dozen reboots and half dozen cold boots. - Reinstalled original GPU, system still worked flawlessly for over a day and a half again with over a dozen reboots and half dozen cold boots. ???? *Scratches Head* - On the morning of the second day without issues the first 3 cold boots locked up. - Before the 4th reboot I swapped to the GTS 250 again and Windows booted fine. - I switched the PC off and swapped back to the 9600 GT, STILL WORKED FINE! - Hair starts to pile up at my feet!!! - 9600 GT is still installed and system is running fine still. * Mobo Bios research: - In a last resort, I checked for possible Motherboard Bios updates. The latest bios available claims to fix "capture card display abnormal when install the PCI Express VGA". - Have yet to install the Bios because of the risk. Could this fix possibly be the answer to all my frustration?! The Computers Specs are below (do not confuse with my signature specs) MOBO: Foxconn P45A-S Socket 775 CPU: Intel Core 2 Duo E7500 2.93Ghz MEM: 4GB (2x2GB) Corsair CM2X2048-6400C5DHX (CL 5-5-5-18) GPU: Galaxy Low Power Geforce 9600 GT 512MB DDR3 256bit (Drivers Forceware 195.62) HDD: Western Digital Caviar Green SataII 500GB - WD5000AADS PSU: Cooler Master 460W M.No: RS0-460-PCAR-A3 Any help would be HUGELY appreciated!!! || || || || \/ These are my specs not the computer in question.