My Air freezes at start up :-( Help me please!

My air has been acting up lately. It kept freezing every two minuts, making the mouse into the colored weel, and occasionally needing to be forced closed.

Now, it freezing while starting up, it shows the grey screen with the apple logo and the 'loading weel' symbol, but never gets any further.

I read that some one with an 2009 macbook pro, had the same problem and that it was his hard drive kabel that needed replacing. Is that my problem too? I would really like it if my problem was something I could fix myself... :-)

I can't live without my mac, I hope there's someone out there that can help me!