MacBook Pro - cd rom error

hi, i'm having a problem with the rom drive on my macbook pro...i was burning a cd in itunes and 3/4 of the way through it spat the cd out. now whenever i click burn cd in itunes it says to insert a blank cd, and when i do it says checking media and a few seconds later it just spits the cd out...same happens when i put an audio cd in, it just spits it back out after about 10 seconds. any ideas or suggestions?

thank you in advance