Hii
Try this
-Boot from CD
- F10 to cancel current upgrade
- Press Enter to setup windows
- Press F8 for license agreement
- Press R for repair
- It will say that it is already in the middle of upgrading to XP, do you want to
retry the upgrade or do a clean isntall? -
- Retry the upgrade
-Else try changing ur Media

Regards
Fazal