Dell inspiron 1521 repair problem help!!!!!!

Ok on my dell inspiron 1521 i have vista home premiumand i boot up and it gets to the loading bar and right before where you can choose you username it goes into a startup repair but it restarts and keeps doing this in a loop. Well i have booted up with the vista home disk and repaired it repairs the boot manager every time i boot or boot from the disk.

the simpliest thing is to do a "format C:" and reinstall SO.
if you have do a complete backup of all files, you'll don't have any trouble in formatting