1) Sounds like your OS got hosed up and you will need to do a HP System Restore, which would wipe it back to when HP first sold it to you
2) You can backup your data getting a ext HD and use Windows Easy Transfer to back it up before you do any more 'damage' or 'fixes'
3) Windows Vista for consumer hasn't been support in years, and if you did try a full RESTORE, you won't be able to patch it up properly anymore as many Vista patches are not available (again not supported), so you may still need to fix this.
4) If you considered getting a new Windows, consider it is $179 off the shelf, now consider a brand new PC at Walmart (Laptop OR desktop) for a i3 is only $249. It would be BEST to just finally replace your system with one that is NOW under warranty AND supported. I would bet dollars that HP would tell you there is no solution because they dont' support that system for years now.