Comment 7 for bug 84780

Your kernel log, dmesg, shows these messages:

[ 98.905709] end_request: I/O error, dev hdb, sector 240121600
[ 98.905733] Buffer I/O error on device hdb, logical block 30015200

These are usually indicative of hardware failure or imminent failure. I recommend using smartctl from the smartmontools package to test your hard drive. I believe a test would look like 'smartctl -t short /dev/hdb' and then you check the output via 'smartctl -a /dev/hdb'.