Xp Restart Help fast please

Hello,

So, I am trying to fix a buddies old computer that is running XP. It's an old HP Pavilion 510n desktop. It starts to load up with the loading bar across the Windows XP Screen, then just reboots. It brings you back to the Error screen (black) with the safe mode, start windows normally and last known good config options. I cannot get this darned thing to load up to even work on it. Nor can I get it to boot from the disk I have. One thing I do know is when you turn it on, there is 1 short beep, and also something like the optical drive making a quick little bit of racket. Please help me out here Im not a time crunch!