Hi wolfamn,
This applies to W98, but perhaps someone with a better working knowledge of XP will confirm for me.. but..
When I have bootup problems in W98, I usually just rewrirte the MBR from a boot disk. This is done by booting up with a startup disk, and typing the following in at the prompt (what you see on the screen is in bold..)
A:\ C:\ {enter}
C:\SYS C: {enter}
Then once it confirms that the files have been copied, reboot the machine.
As I say, that's 98.. anyone know if that works in XP?
Cheers
Liam