I have a unique situation that is extremely similar to numerous well-documented issues. Unfortunately, it will take some creative ideas to fix this. I was running Windows XP Professional SP3. An annoying trojan made it through my internet security settings. Norton caught it. I used Norton Power Eraser to get rid of it (rootkit or something). There was one file that couldn't be deleted, thought. Norton said that to fix the problem, I should boot from my XP install disk and repair the installation, which would replace the file. I did so, and rebooted. Here, the actual problem begins. After rebooting, windows will not start. The splash screen appears briefly, followed by a BSOD and reboot. Booting in Safe Mode reaches Mup.sys and then reboots. Eventually, I managed to turn off AutoReboot on error even though I can't get into windows, so I could read the BSOD. Page error in non-paged area, stop error 0x00000050 After another day of research, I found that Windows XP with SP1 has this issue, caused by incompatible drivers. Why does this matter, since I was running SP3? Simple. My Windows installation disk is Service Pack 1a. So when I performed a repair on my windows installation, the files were replaced with versions from Service Pack 1, which have a conflict with some of my installed drivers. So, I need a way to identify which drivers are causing the problem so that I can delete them, and boot into Windows so that I can download and reinstall SP3, then reinstall the drivers. I have an Ultimate Boot CD for WinXP, so I can access the hard drive, but I can't get into my Windows installation to do anything. So, can anyone help me identify the offending drivers?