I have a 2008 MacBook. Have been burning CD's and I can not get the last CD into computer. Acts like it is blocked or locked. How do I unlock it?

I have a late 2008 MacBook and have burning some CD's. It has been working just fine. I tried to insert the last CD and can not insert it. it acts like it is locked or blocked. how can I get it to work again? I have tried restarting it several times, tried restarting it while holding done the esc key and the pad key. Nothing has worked so far.

Any clues other than taking it in???