unable to boot

[norman]

I have an old desktop machine which has used Ubuntu for more than 2
years and now I am happily using a new machine with Ubuntu. I decided to
convert the old machine to Win 2k to use for games etc. So, I started
set up and reformatted the HDD and the installation went as far as
telling me that the computer would reboot. Computer closed down and then
restarted and got as far as 'Error loading operating system' and
stopped.

I wondered if anyone else had seen a similar problem when trying to
convert a Ubuntu machine to a window's one? If so, is it possible to
overcome this difficulty?

Norman