Y'know, I just went thru the same runnish with both my CDR/RW and then a month later with my DVD-ROM.
It all started when my CD unit would no longer recognize CD-R discs, but it WOULD recognize CD-RW discs. Shortly after that it wouldn't read either of them in Linux, and in WinXP it wasn't working right either.
Then suddenly, my DVD player would read computer discs, like to install an OS, but it wouldn't play movies at all, it just sat there making noises and flashing its lights.
The solution: Take apart the unit and clean the lens with a Q-tip and alcohol.
This worked miraculously with both my drives, and both work like new again.
NOTE: if your drive is pretty new, this is likely not the issue. Mine are just over 3 yrs old, and had accumulated a film of smoke and crap on the lens. Cleaning disks were useless, it needed a real cleaning with an alcohol swab.