Hey there. Yesterday I got my dad's used C2D MacBook to replace my CD MacBook. Everything worked fine when I was transfering everything over, but when I got home and booted it up, I noticed that in addition to the normal optical drive sounds the MacBook makes, this had a weird grinding/vibrating sound. I did replace the RAM in the notebook, but I checked down there again to see if I had left anything loose that could possibly be making the vibrating/grinding, but it is all tight. Now, the MacBook only makes the grinding on start up. If I put in and eject disks while the computer is on, it doesn't make the noise at all. Is this something I should worry about?