Comment 2 for bug 728208

Your harddisk is about to die:

[14440.086271] sd 0:0:0:0: [sda] Unhandled sense code
[14440.086273] sd 0:0:0:0: [sda] Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE
[14440.086277] sd 0:0:0:0: [sda] Sense Key : Medium Error [current] [descriptor]
[14440.086283] Descriptor sense data with sense descriptors (in hex):
[14440.086285] 72 03 11 04 00 00 00 0c 00 0a 80 00 00 00 00 00
[14440.086296] 02 af fd de
[14440.086301] sd 0:0:0:0: [sda] Add. Sense: Unrecovered read error - auto reallocate failed
[14440.086307] sd 0:0:0:0: [sda] CDB: Read(10): 28 00 02 af fd d8 00 00 08 00
[14440.086318] end_request: I/O error, dev sda, sector 45088222
[14440.086336] ata1: EH complete
[14440.086345] EXT4-fs error (device sda2): ext4_find_entry: inode #1314436: (comm dpkg) reading directory lblock 0
[14440.086351] Aborting journal on device sda2-8.
[14440.087169] EXT4-fs (sda2): Remounting filesystem read-only

You should backup your data and install a new one.