I have an Asus n56v and I've got troubles installing Ubuntu 12.04 x64.

I already have installed Windows 7 x64!

The hard drive is: Hitachi HTS547575A9E384

My problem:
The installation program doesn't recognize the already existing partitions and is offering only options where there are partitions.

Can someone help me out?

Is this an ACPI/IDE conflict, missing driver or conflict with Windows 7?

(I'm not an expert on Linux, only working sometimes with it.)

I now tried out some options concerning EFI with a GTP-table. Everything worked but I wasn't able to fix a dual boot (Windows boot loader) nor with GRUB2.

The laptop is still having a BIOS, but is able to boot DVDs/CDs in EFI-mode.

Now I try to avoid EFI and GTP using the old windows MBR style. I reinstalled Windows, so far no problem.

When I want to try to install Ubuntu, it doesn't detect the already existing partition table. It is just showing me an empty space for the whole disk.

Other threads like Ubuntu 12.04 does not see windows already install on my computer (dual installation) don't help me out.

os-prober shows me a correct result.

I don't know how to deal with gdisk as shown in Installer doesn't detect existing partition table/windows 7 partition.

I have 750GB for the whole disk. I'm using: 90GB for Windows reserved partition + system partition, 500GB for data and the rest should be for SWAP and linux-system.

How can I make Ubuntu detect the partition table?