If you boot a computer that also has OS/2 2.x installed, you receive:
Windows NT could not start because the following file is missing or corrupt: <winnt root>\System32\Ntoskrnl.exe.
The OS/2 Boot Manager creates another primary partition that is enumerated before any extended partition.
To resolve the problem:
1. Open a cmd prompt and switch to the root folder.
2. Attrib -R -S -H c:\boot.ini.
3. Edit the Boot.ini file and change the partition number (usually you increase it by 1).