Safe Boot Problem

My 2009 macbook pro isn't starting up correctly. First, safari started running slow. Soon after, the computer would stop loading at the blue screen. I'm able to get to the safe boot startup screen (where it asks for my password). I enter my password, click log in, the box disappears, and there's nothing on the screen except for the pointer and the standard purple spacey background for several mintues. The password screen then pops up again. This repeats over and over again. What might this mean? It's obviously the correct password since the box shakes if I enter a wrong one. It's accepting the password but not fully loading up. Thanks so much for the help.

 

I havent changed anything about it lately. I really only use it for internet.

I did an extended hardware test (w/o the disc, I can't find it right now). It found an error: 4HDD/11/40000000: SATA (0,0).

Thanks for any help

 

damn, is that expensive? Whenever I turn on the computer, it does make a noise, like gears turning or something. I guess that's the HD failing.

 

I don't know a lot about technical computer stuff, but if I put a new drive in I'll lose everything that was on my computer like my itunes songs and word documents?

 

I do, the computer I'm using right now is my mom's macbook pro. We also have an Imac. But since I'm able to get to the safe boot start up screen, isn't there a chance a I can access the computer again?

 

alright, what kind of firewire cable do I use? do I have to go out and buy a special one?