I have pretty much the exact same problem as you, although it has been going on for quite a while now. CDs read fine, as do pressed DVDs, but DVD-R/DVD+R discs just don't work - it refuses to read them. Spins up, then spins down then everything hangs a little until i press the eject button.
It is really strange that it burns fine, yet refuses to read the discs it has burned. I have tried three types of media, both DVD-R and DVD+R and I get the same results. I'm going to try it in another computer to see if it is the same there. If it is, I intend to buy a new drive - I've tried pretty much everything I can think of for months, but to no avail.