$ sudo fdisk /dev/sda

Command (m for help): p

Disk /dev/sda: 257 MB, 257949696 bytes
8 heads, 62 sectors/track, 1015 cylinders
Units = cylinders of 496 * 512 = 253952 bytes

This doesn't look like a partition table
Probably you selected the wrong device.

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   ?     1568823     3870254   570754815+  72  Unknown
Partition 1 has different physical/logical beginnings (non-Linux?):
     phys=(357, 116, 40) logical=(1568822, 3, 11)
Partition 1 has different physical/logical endings:
     phys=(357, 32, 45) logical=(3870253, 0, 51)
Partition 1 does not end on cylinder boundary.
/dev/sda2   ?      340100     4243383   968014120   65  Novell Netware 386
Partition 2 has different physical/logical beginnings (non-Linux?):
     phys=(288, 115, 43) logical=(340099, 6, 47)
Partition 2 has different physical/logical endings:
     phys=(367, 114, 50) logical=(4243382, 4, 42)
Partition 2 does not end on cylinder boundary.
/dev/sda3   ?     3769923     7673205   968014096   79  Unknown
Partition 3 has different physical/logical beginnings (non-Linux?):
     phys=(366, 32, 33) logical=(3769922, 2, 30)
Partition 3 has different physical/logical endings:
     phys=(357, 32, 43) logical=(7673204, 7, 39)
Partition 3 does not end on cylinder boundary.
/dev/sda4   ?     5817906     5818018       27749+   d  Unknown
Partition 4 has different physical/logical beginnings (non-Linux?):
     phys=(372, 97, 50) logical=(5817905, 4, 25)
Partition 4 has different physical/logical endings:
     phys=(0, 10, 0) logical=(5818017, 3, 33)
Partition 4 does not end on cylinder boundary.

Partition table entries are not in disk order