hda: read_intr: status=0x59 { DriveReady SeekComplete DataRequest Error } hda: read_intr: error=0x40 { UncorrectableError }, LBAsect=5221126, sector=1

^^^^^^^^^^^^^^^^^^ That's your cue!

There's a physical error (bad sector) on your hard disk. UncorrectableError means there was a burst error severe enough that the ECC algorithm couldn't correct it. If you can read other partitions from the same hard disk, there's a good chance that it is only a few bad sectors and most of your data is intact.

Your best bet is to somehow boot to Windows or DOS 7.x and run Norton Disk Doctor. Don't bother running scandisk. It'll say something like "Errors in Filesystem, Scandisk can't run" (duh!)

If that doesn't work, and you have sufficiently important data on that disk let me know. If enough of the filesystem tables are intact it ought to be possible to fix it manually.

Anyway ultimately you want to do a low-level format of that hard disk before you use it again.