Mac Book Pro 15' OSx Lion Loading Problem?

[Syro]

I have the newest version of Lion. I'm currently on it under the recovery disk. I was just using it with no problems at school a few hours ago, then when I got home I turn it on. I get to the loadup screen, type in my password, and suddenly the login screen goes away and I get a blank white screen. Seconds later, it sends me straight back to the login screen. I tried logging in constantly for at least 10 minutes. Sometimes the grey loading circle appears for a second, but then it just sends me back to the login screen. I've tried entering in a wrong password and it just shakes the screen like normal. I repaired my disk and it said successfully repaired. I can't think of what could have caused it. I haven't installed any new programs in days. I really need to find a solution to this without erasing my HDD. Everything I've ever done at school and all my music software, songs in progress, ect ect are on here and I have not had a chance to back it up since my external HDD is not at my current residence. And also, I doubt its my harddrive because, well my safari works, my picture saved on my HDD that I see when I login is there. This computer is only about 1 month old. Any help is appreciated, thanks in advance.