My Imac G5 Ejecting disks

I am currently using my Imac G5..it used to play dvd's cd's music cds,etc..
Now..its not taking those dvds or cd's anymore, its just ejecting my Cd or DvD evertime i insert it. i dont no what i have done wrong can someone please help me?..if so thanks in advanced, and btw does mac need Idvd to be able to recognise my cd's or dvd's?

how old is your machine ? I have one of the first batches of those machines....The same thing happened to me, but only with my DVD's. My superdrive was knackered and needed replacing.

umm its Imac G5 and ure probally right my superdrive is recked. its not old i got it last year 2006 start of that year lols. im really angry not because i like watching dvd's or cd's i hardly use it for that, the reason im angry is that i cant play world of warcraft and the holidays are coming up and there are NO other games for mac that are good lols.