lokokkee

I have a Creative DVD -/+RW 8x/4x/2x and a Lite-On DVD rom drive on a self-assembled PC running WinXP Pro. The former just lost the ability to read and write CDs, i.e. the drive is shown as empty with a CD in it, but works perfectly with DVD medium. The latter won't run DVDs on auto-run start up, but works well as the source drive when copying DVDs, and no problem at all with CDs.
Question 1 - do DVD drives have two laser pick-ups, one for DVD and another for CD, so that if the latter is kaput, that will explain my Creative drive's behaviour.
Question 2 - the same DVD will autostart on the Creative drive, but won't on the Lite-On. Thought the softwares that run the drives are the same, and the drive will play Win Media Player if started manually, so what could be the problem?