Why won't my optical drive open unless there is a disc in it?

I bought my eMac (1.25Ghz, USB 2.0, MacOS 10.5.8) from my school last Friday, and have been fixing little glitches, deleting old files, etc. I've finally gotten everything in almost perfect working order except the optical drive. The drive itself seems fine and reads CD's no problem. The only problem is that the drive won't open on it''s own, I have to use the little paperclip hole everytime I want to open it. However, once the disc is in, it will read and eject the disc normally, but once the drive is empty again, I have to use the paperclip to get it open. I don't know if it's a hardware or software malfunction. Help!?

P.S. It also spits out DVD's. I thought it was supposed to be able to read them (it reads CD's just fine), but it just gives DVD's back.