I upgraded a computer with an ASUS P5LD2 mobo, an Intel DuoCore CPU and 2 100gb SATA RAID drives (Raid 0). I was running XP SP2. All worked fine when I first assembled it. A few months later I loaded Vista, which caused multiple compatibility problems, so I tried to go back to XP. Now it no longer recognizes the hard drives, though I loaded the drivers as usual. When I hit either ENTER or DELETE where it asks me to select a partition, I get the infamous Blue Screen of Death, and a message that says: A problem has been detected and windows has been shutdown to prevent damage to your computer. The problem seems to be caused by the following file: setupdd.sys PAGE_FAULT_IN_NONPAGED_AREA. If this is the first time you've seen this Stop error screen, restart your computer. If this screen appears again, follow these steps: Check to make sure any new hardware or software is properly installed. If this is a new installation, ask your hardware or software manufacturer for any windows updates you might need. If problems continue, disable or remove any newly installed hardware or software. Disable BIOS memory options such as caching or shadowing. If you need to use Safe Mode to remove or disable any components, restart your computer, press F8 to select Advanced Startup Options, and then select Safe Mode. Technical Information: *** STOP:0x000000050 (0xE57A1868, 0x000000000, 0xF752F9A8, 0x000000002) *** setupdd.sys - Address F752F9A8 base at F7508000, DateStamp 41107c8f The date stamp varies, but the rest is the same. I don't know how to turn off cache-ing in CMOS setup. When I go back to Vista, everything loads up without a hitch, so how could it be hardware? Also, it happens during setup, so how could it be software? Some things I have tried: *swapping out memory cards *using different XP disks *Running anti-spyware/anti-trojan software *Running memtest (no errors after an hour) I guess I am stuck with Vista unless I can figure this out. Any ideas?