Ubuntu installation does not recognize drive partitioning

I have a 1TB drive and installed Windows 7 on a 128GB partition.

When I now try to install Ubuntu 11.04 it does not recognize the Windows partition but offers the complete 1TB drive to install Ubuntu on instead. It displays:

However, in the Ubuntu Disk Utility the Windows partitions are recognized.

What do I need to do in order for Ubuntu to recognize the Windows 7 partition and install Ubuntu as a dual boot?

Response to comments

The following commands were executed and the results are shown below:

fdisk -l

WARNING: GPT (GUID Partition Table) detected on '/dev/sda'! The util fdisk 
doesn't support GPT. Use GNU Parted.

Disk /dev/sda: 1000.2 GB, 1000204886016 bytes
255 heads, 63 sectors/track, 121601 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x34a38165

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *           1          13      102400    7  HPFS/NTFS
Partition 1 does not end on cylinder boundary.
/dev/sda2              13       16318   130969600    7  HPFS/NTFS

Disk /dev/sdb: 500.1 GB, 500107862016 bytes
255 heads, 63 sectors/track, 60801 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x14a714a6

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1               1       60801   488384001   83  Linux

parted -l

Warning: Unable to open /dev/sr0 read-write (Read-only file system).  /dev/sr0
has been opened read-only.
Error: /dev/sr0: unrecognised disk label                                  

I can proudly announce that I now have a working Windows 7 and Ubuntu 11.04 running.

fixparts actually did the trick:

Download fixparts and run it with

sudo fixparts /dev/sda

fixparts then wants to know if it should Erase GPT data which I desperately did, and apparently repaired the partitions.

Ubuntu was then able to find the windows partition and installation worked like a charm.

Thx to arrange for the hint!