If it's spitting out factory-pressed DVDs (I'm taking your "all DVDs" literally), then your drive is likely toast. Dual-laser drives use an IR laser for CDs, and a red one for DVDs. The red laser is the more fragile of the two, and if it dies, you get the behavior you're observing.

Now, I don't know if your drive has two separate lasers, but many do (in order to maximize compatibility with the various flavors of recordable media).