Debugging a Dual-Boot Machine
How should you respond when the alternate operating system does not start on a dual-boot machine?
First, check that the boot options point to the correct path for the other operating system. See Getting Set Up for Debugging for details.
On an x86 computer, you should also verify that boosect.ini exists. This file contains the boot record for the other operating system. To unhide this file, use the attrib -r -s -h boosect.ini command.