I am trying to download windows 7 on my macbook pro but it keeps saying the disk cannot be partitioned because some files cannot be moved.

Its all in the title. I am trying to use bootcamp to download windows 7 on my macbook pro mountain lion, but I keep getting this error. I tried going to Disk Utility, and my active volume already is formatted under Mac OS Extended (Journaled), so I don't know how to fix it. I already backed up the volume on an external harddrive. Also, everything under the volume I wanted to edit is greyed out, and when I try to restore the backup that I created via time machine, it pops up with another error that says "Could not unmount volume "/" (Resource Busy).

Please be gentle, I'm used to using windows and don't know like anything about computers. If someone could give me a detailed explanation for these errors and a solution of how I could correctly download windows on my mac I would greatly appreciate it. Thanks!