Install Ubuntu 12.04 64bits on dell XPS 14 ultrabook

I cannot install Ubuntu 12.04 64 bits on my new dell XPS 14 ultrabook. When I tried to install it from a usb drive or wubi the installer says: "No root file system selected".

The problem is that I cannot see my hard drives and I cannot create a new partition, delete one, etc., bc the buttons are disabled.

Hardware:

• 3rd Generation Intel® Core™ i7-3517U processor (4M Cache, up to 3.0 GHz)
• 14.0" HD+ (900p) Truelife Infinity Display with Skype-Certified Hi-Def Webcam
• 8GB2 DDR3 SDRAM at 1333MHz
• 500GB 5400 HDD with 32GB mSATA
• NVIDIA® GeForce® GT 630M with 1GB GDDR5 VRAM

Any ideas?

Thanks in advance.

why don't you try this? I remember coming across a problem similar to yours.

Run this command as root:

dmraid -E -r /dev/sdX

Where 'X' is the letter that identifies your actual device.

Source: http://www.pendrivelinux.com/ubuntu-installer-cant-find-my-sata-drive/