Loud noise from superdrive

Hi everyone

I have a problem, I hoped someone in here could help me with.
My Macbook (from 2008) has begin to suddenly, completely randomly to make a lot of noise. Like it is makes the noise, it usually do at startup a few times in a row. I am not even having anything in the drive. Often when I only use word.. It is this sound.

I have absolutely no clue why

Hope, someone can help.

Kind regards,
Katrine

I know, it is normal for start up, but I don't think it is normal that it do this sometimes five-seven times in a row when the only application running is word?