A friend’s PC had lost its ability to dual boot (Windows 2000 for work and Windows 98 for games). I had installed BootMagic to switch operating systems some years ago and it worked fine until it was broken this month during some harddisk cleanup.
I completed the cleanup of the Win98 partition with a new installation. After installing PartitionMagic and BootMagic again, Bootmagic would still not work, and the Windows 2000 installation (which I didn’t touch) booted, but after a successful log on I was always logged out immediately.
I tried several things and searched for keywords like logout immediately after login and login failure without finding something helpful. Later I realised that the official terminology is log on/off, not login/logout…
I then observed that chkdsk had detected FAT32 for the C: drive and NTFS for E:. This let me suspect a problem with drive letters (The NTFS partition should be C:), and when I googled for drive letter related pages I found my solution in the Microsoft Knowledgebase: KB 249321.
Of the different suggested possibilities I had to use the “fake-system-folder” approach. I booted from a Knoppix CD and copied userinit.exe to the Windows 98 partition. Then I could log on without getting kicked out immediately; but I had only an empty screen without icons and taskbar. But Ctrl-Alt-Del let me start first Task Manager and then regedit and I managed to edit the registry as described in KB 223188 and get back a working Windows 2000.