Existing partitions are not being detected during installation

[aman41907]

Hi,
I am trying to install ubuntu 11.10 over windows 7.I have 160 GB hardisk which is divided in 4 partitions and arround 30 gb unallocated space.But when I try to install ubuntu ,My partitions are not being detected.Even gparted is not able to detect the partitions.

The output of sudo fdisk -lu is

Disk /dev/sda: 160.0 GB, 160041885696 bytes
255 heads, 63 sectors/track, 19457 cylinders, total 312581808 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: 0xdd36dd36

Device Boot Start End Blocks Id System
/dev/sda1 * 63 81915434 40957686 7 HPFS/NTFS/exFAT
/dev/sda2 81915435 312560639 115322602+ f W95 Ext'd (LBA)
/dev/sda3 163830933 245746304 40957686 7 HPFS/NTFS/exFAT
/dev/sda5 81915498 103410404 10747453+ 7 HPFS/NTFS/exFAT
/dev/sda6 103410468 163830869 30210201 b W95 FAT32

Disk /dev/sdb: 4012 MB, 4012900352 bytes
120 heads, 55 sectors/track, 1187 cylinders, total 7837696 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: 0x00000000

Device Boot Start End Blocks Id System
/dev/sdb1 32 7837695 3918832 b W95 FAT32

Disk /dev/mapper/live-rw: 4294 MB, 4294967296 bytes
255 heads, 63 sectors/track, 522 cylinders, total 8388608 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O si GiBe (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000

Disk /dev/mapper/live-rw doesn't contain a valid partition table

Disk /dev/mapper/live-osimg-min: 4294 MB, 4294967296 bytes
255 heads, 63 sectors/track, 522 cylinders, total 8388608 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: 0x00000000

Disk /dev/mapper/live-osimg-min doesn't contain a valid partition table

when i run gparted I get following information

file system : unallocated

Size: 149.05 Gib


Any help is appreciated

[oldfred]

It looks like your sda3 a primary, is inside the extended partition which is not possible. Only logical partitions can be inside the extended.

You may be able to change it to a logical.

Back up partition table first with this and save this file to another device:
sudo sfdisk -d /dev/sda > parts.txt

To convert a partition from primary to logical, at least one free (unallocated) sector must exist between the partition and the one that precedes it.
Fixparts - Repair broken partition tables (not overlapping issues) & delete Stray gpt data from MBR drives
http://ubuntuforums.org/showthread.php?t=1705325
http://www.rodsbooks.com/fixparts/