Many times when I try to put a dvd into my macbook, it acts like there's already a dvd in it. It gets about halfway in and feels like it just hits a wall. I have to continuously stick the dvd in, then pull it out until the disk finally goes all the way in. I haven't had any problems ejecting the disk, or having the disk pulled in once it gets in far enough for the laptop to recognize a disk is being stuck in it. Any ideas what could be the problem?