[ubuntu] invalid patition table error on 12.04 boot up

Code:

# fdisk -l

Disk /dev/sda: 500.1 GB, 500107862016 bytes
255 heads, 63 sectors/track, 60801 cylinders, total 976773168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk identifier: 0x000edbe5


   Device Boot      Start         End      Blocks   Id  System
/dev/sda1            2048   943368191   471683072   83  Linux
/dev/sda2       943370238   976766975    16698369    5  Extended
Partition 2 does not start on physical sector boundary.
/dev/sda5       943370240   976766975    16698368   82  Linux swap / Solaris


Disk /dev/sdb: 500.1 GB, 500107862016 bytes
255 heads, 63 sectors/track, 60801 cylinders, total 976773168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk identifier: 0x000edbe5


   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1            2048   943368191   471683072   83  Linux
/dev/sdb2       943370238   976766975    16698369    5  Extended
Partition 2 does not start on physical sector boundary.
/dev/sdb5       943370240   976766975    16698368   82  Linux swap / Solaris


Disk /dev/mapper/isw_dfciehgfed_Volume0: 500.1 GB, 500104826880 bytes
255 heads, 63 sectors/track, 60800 cylinders, total 976767240 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk identifier: 0x000edbe5


                              Device Boot      Start         End      Blocks   Id  System
/dev/mapper/isw_dfciehgfed_Volume0p1            2048   943368191   471683072   83  Linux
/dev/mapper/isw_dfciehgfed_Volume0p2       943370238   976766975    16698369    5  Extended
Partition 2 does not start on physical sector boundary.
/dev/mapper/isw_dfciehgfed_Volume0p5       943370240   976766975    16698368   82  Linux swap / Solaris


Disk /dev/mapper/isw_dfciehgfed_Volume0p1: 483.0 GB, 483003465728 bytes
255 heads, 63 sectors/track, 58721 cylinders, total 943366144 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk identifier: 0x00000000


Disk /dev/mapper/isw_dfciehgfed_Volume0p1 doesn't contain a valid partition table
fdisk: unable to read /dev/mapper/isw_dfciehgfed_Volume0p2: Inappropriate ioctl for device
root@kr:~# mount
/dev/mapper/isw_dfciehgfed_Volume0p1 on / type ext4 (rw,errors=remount-ro)
proc on /proc type proc (rw,noexec,nosuid,nodev)
sysfs on /sys type sysfs (rw,noexec,nosuid,nodev)
none on /sys/fs/fuse/coections type fusectl (rw)
none on /sys/keel/debug type debugfs (rw)
none on /sys/keel/security type securityfs (rw)
udev on /dev type devtmpfs (rw,mode=0755)
devpts on /dev/pts type devpts (rw,noexec,nosuid,gid=5,mode=0620)
tmpfs on /run type tmpfs (rw,noexec,nosuid,size=10%,mode=0755)
none on /run/lock type tmpfs (rw,noexec,nosuid,nodev,size=5242880)
none on /run/shm type tmpfs (rw,nosuid,nodev)
gvfs-fuse-daemon on /home/x/.gvfs type fuse.gvfs-fuse-daemon (rw,nosuid,nodev,user=x)