A fairly common difficulty, that may or may not be applicable here, is that the read/write lens in your drive may have picked up a trace of smog. Mine seems to accumulate cat hair.

Sometimes a lens cleaning, using one of those CD disks with the little whiskers on it (usually under $5 US?) will get you back in operation. While it's only a "maybe it's this" thing, it's so cheap to do that it is worth keeping one of the cleaning disks around. More elaborate "cleaning kits" are available, but a run with the simple one may indicate whether this is part of your problem.

John