Xp ne démarre pas

Bonjour j'ai un problème avec mon pc il ne démarre pas .
il affiche ce message:
a problem has been detected and win has been shut down to prevent damage to your computer UNMOUNTABLE_BOOT_VOLUME
If this is the first time you've seen this stop error screen , restart you computer . if this screen appears again follow these steps:
check to make sure any new hardware or software is properly installed.
if this is a new installation ask you hardware and software manufacturer for any windows update you might need.
If problems continue disable or remove any newly installed hardware or software.Disable bios memory option such as caching or shadowing.If you need to use safe mode to remove or disable component, restart your computer press F8 to select advanced startup option and then select safe mode.
comment resoudre ce problème ?