I installed lubuntu from alternate cd a month ago. Now when I needed to read some cd's, the cd try won't open. It can be opened before ubuntu boots up. It can be opened after entering sudo eject -i off from console. But it won't mount any other cd-roms, than just the lubuntu live-cd and lubuntu alternate instal cd, where it was installed from. "mount: no medium found on /dev/sr0" as output, when try to mount anything else. Problem can't be in corrupted sd's, because othe computer, did recognize them well.