If you can't even read finalized discs, try different media. Some drives are quite finicky about the types of discs they'll accept (and in my experience, Apple/Matsushita drives are more troublesome in this way than most others are). Aside from the -R vs. +R question, there's also -RW and +RW. And even within those types, different brands/speeds may behave differently.

Generally speaking, higher quality media will give you less trouble (big surprise, huh?), but you may still encounter difficulty. Some experimentation may be in order.