Comment 2 for bug 137128

The log says:

Sep 3 14:35:56 ubuntu kernel: [ 1511.590802] sr 1:0:0:0: SCSI error: return code = 0x08000002
Sep 3 14:35:56 ubuntu kernel: [ 1511.590812] sr0: Current: sense key: Medium Error
Sep 3 14:35:56 ubuntu kernel: [ 1511.590817] Additional sense: No seek complete
Sep 3 14:35:56 ubuntu kernel: [ 1511.590825] end_request: I/O error, dev sr0, sector 14744
Sep 3 14:35:56 ubuntu kernel: [ 1511.590834] Buffer I/O error on device sr0, logical block 3686
Sep 3 14:36:00 ubuntu kernel: [ 1515.687520] SQUASHFS error: sb_bread failed reading block 0xfe4

... and it all goes downhill from there. That is, the system fails to read from the CD - at that point there's not a lot the installer can do since its own code is read from the CD! (Future kernel versions will detect this better and it'll probably show up as an I/O error rather than a segfault, though.)

This particular error is often due to a faulty CD/DVD disk or drive. It may help to clean the CD/DVD, to burn the CD/DVD at a lower speed, or to clean the CD/DVD drive lens (cleaning kits are often available from electronics suppliers).