This week my more than 3-year old Asus 1608P2S started dying. Occasionally, the tray would not open and finally it stopped recognizing any discs and refused to work at all. After restarting Windows it started working again but something was wrong - the read speed was very slow and when copying files from a DVD+R the CPU usage stayed at 100% and I experienced jerkiness when moving mouse cursor and windows. I checked the cables and connectors but it didn’t help. Because I need a DVD writer in my daily use I simply bought a new Pioneer DVR-116D, which worked without any problems as expected. The next day I though maybe I can look inside my old Asus before I throw it away. I opened the metal case, looked around the drive’s bowels and cleaned any dirt and dust I could see - the laser seemed to be clean anyway. I put it all together again and after connecting it to my computer the drive started working well! The reading issue is gone and it seems to burn all right! I just wish I did it before I bought the Pioneer, now I have 2 drives and both work. At least the DVD drives are quite cheap now.
Conclusion: if you have a drive that refused to work, try cleaning it before you throw it away as there may be some hope!