I have had my Mac OSX(10.5.7) for 3 years and have always played and burned cd's with no problems.However this morning all of a sudden it's not reading any cd's I put in.They just pop out after a few seconds.Blank cd's and cd's with stuff on them.It doesn't make any sound at all the cd just pops out after a few seconds.What could the problem be and how do I fix it?