BIOS must be set to boot to CDRom.
Additionally, since there is an installed OS on your hard drive, you must press a key during the boot when it asks you to do o or it bypasses the CD and goes to the HD anyway.
Once booted on teh CD you can delete the partiton and start over.
I have tried at reboot but the computer does not see cdrom and (dos prompt )format c: /q /fs not work either nothing not even the old format c/: /s why cant I get control of this and reninstall the whole thing, oh if you can help, please cause it just crashes and crashes and every malware and spyware has been removed even the trojans and viruses but it wont work now on sims2. old app were removed wrong thanks to my children. if you can help please email me now????!!!!