I'd been having problems with my CD/DVD drive. Yesterday it finally died. Unfortunately it was during a OS installation. At some point the installation would fail, usually with a message blaming failure to read the CD. I'd tried cleaning the drive with a lens cloth, so I more or less gave up on that computer, putting it aside for when I could afford a new CD drive.
Then, on my old computer, I thought I'd have a quick Google and see if I could find any advie that might resurect the drive.
One site I found recoomended cleaning the drive with a photographic lens cleaner- the type that blows air through a soft brush- and using 100% alcohol on a Q-tip in a circular motion.
I don't have a lens cleaner, but I found an old baby nose cleaner bulb- somewhat snotty but dry- some Turkish lemon cologne and a cotton bud. After some careful blowing around and cleaning of the laser lens, the drive was working again.
I was quite surprised, because I'd had a look at the lens through a powereful magnifying glass and it looked perfectely clean. Obviously even an invisible film of dirt can affect the laser beam. A tip worth remembering, but for best results, look for a real lens blower and proper cleaning alcohol.