Dell Notebook 1520, DVD RW not run old CDs

Hello,

I have an Dell Inspiron 1520 brought on Jan'08. In the last few days what I have seen that in my DVD RW when i insert new CDs it runs but when i insert old CDs like 2-3 like usage or DVDs it does not run. When I contacted to Dell Tech.Support, they told me that there is problem of BIOS or CD/DWR software updation.

Request you all friends to kindly advise me is there is a problem in DVD RW or other.

Reds: Raj