Yeah the doors can get stuck sometimes. In fact, my brand new Sony drive sticks for a second, and sometimes I have to press the button twice before the drive pushes open the door and slides open.
That shouldn't have anything to do with CDs or DVDs not burning though. Usually when a drive doesn't recognize that a CD or DVD is in the drive it's because it just doesn't like that particular batch, or even brand, of disc, and swapping to another brand usually sorts it out.
If it doesn't, though, then there are some nice cheap drives
on Ebuyer that'll set you right. Just be sure to check whether your existing drive is IDE or SATA. (Or at the very least, as most drives are SATA these days, just make sure you've got a free SATA slot on your motherboard. They're usually orange, about a centimetre long, and usually come in pairs. They look like
this.)