My mother sent me a video this morning of her PCs DVD drive opening and closing randomly and erratically. In fact, so erratically, sometimes it would barely open before closing again. Now, I know it's defective, and most likely needs to be replaced, but I couldn't really explain to her what caused it besides the fact that DVD drives are THAT mass produced that if you go on any website you'll see tons of bad reviews even on a 4 or 5 star product.
I've never seen this happen, save for my laptops drive opening itself if there wasnt a disc in the drive, but never closed it didnt have that function.

What exactly happens that a drive goes bad like that? anyone have more experience?