liteon dvd-rom doesn't recognise dvds

[whatthe]

This is a similar problem to the thread trancy1 started but i just want to know more about the problem.
My dvd-rom (i've only had for a year or so) does not recognise any dvds at all but it can read cds just fine. When I insert a dvd it tries to read it and when i click on the drive to explore it, it says to insert a disc. I tried the dvds on another dvd-rom drive and that worked fine (so it can't be the dvd), i'm totally mystified as to what happened with my dvd-rom??
I took it out to check the connections and that was fine too, but when i shook it a little i heard something rattling inside (like something was inside and rolling around). Is this normal and is it at all possible for your dvd-rom to partially work like mine does.
I want to pull it apart and check it out but I thought i'd post this message up first before i damage the drive completely by pulling it apart.

Thanx

[setarip]

Your player probably has dual lasers - one specifically for DVDs - and it may have gone out of alignment. If so, it will prove less costly to purchase a new one than to repair your present one...

[whatthe]

Thanx dude. I didn't know they had dual lasers. Would you happen to know how this could happen and what i can do to prevent it from happening again?

Cheers

[setarip]

As I mentioned in my post to trancy1's thread, you can try using a DVD/CD cleaning disk. If that doesn't work, it's probably time to spend $40US for a new DVD ROM...