I have problem with overlapping partitions. GParted shows me all my disk as unallocated area, output of fdisk below:

alex@alex-ThinkPad-SL510:~$ sudo fdisk -l /dev/sda

Disk /dev/sda: 320.1 GB, 320072933376 bytes
255 heads, 63 sectors/track, 38913 cylinders, total 625142448 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0xfb4b9b90

  Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *        2048     2457599     1227776    7  HPFS/NTFS/exFAT
/dev/sda2         2457600   571351724   284447062+   7  HPFS/NTFS/exFAT
/dev/sda3       571342846   604661759    16659457    5  Extended
/dev/sda4       604661760   625137663    10237952    7  HPFS/NTFS/exFAT
/dev/sda5       598650880   604661759     3005440   82  Linux swap / Solaris
/dev/sda6       571342848   598650879    13654016   83  Linux

Partition table entries are not in disk order

Do I understand correctly that overlapping partitions are sda2 and sda3 (sda2 and sda6 overlaps too, because sda6 is the first chunk of sda3, sda3 has type "extended")? Are sda2 and sda3 the cause of problem? How can i fix it without deleting partitions?

My OS is Ubuntu 12.04, 64 bit. Thanks in advance.