Unmountable_boot_volume?

my friend has a problem she has the blue screen saying unmountable_boot_volume i have read answers already on here but i am unable to get any of it to work i placed the xp disk in the drive and switch on the pc i have a black screen which i can not enter any thing excepts press delet on for setup if i dont press the delet on i get the screen asking if i want to startin safe made,safemade networking,safemade command prompt ,from time configuration was accepted or start windows normally if i press any of these it just goes back to the blue screen please can anyone help