Estoy siguiendo mis investigaciones. He visto que el error que me suele dar y por el cual no me deja instalar windows en la partición "estropeada" dice: bla bla bla disc 1 bla bla MBR
He estado investigando y he encontrado esta posible solución para reparar eso:
The simplest way to repair or re-create MBR is to run Microsoft's standard utility called FDISK with a parameter /MBR, like
A:\> FDISK.EXE /MBR
FDISK is a standard utility included in MS-DOS, Windows 95, 98, ME.
If you have Windows NT / 2000 / XP, you can boot from startup floppy disks or CD-ROM, choose repair option during setup, and run Recovery Console. When you are logged on, you can run FIXMBR command to fix MBR.