Existing partitons not recognized during installation

view story

http://askubuntu.com – I've got a Windows 8 (final version, no preview) installed in my pc. Now I wanted to install Ubuntu like I've done a thousand times before. Strange thing is, gparted (started from live USB-Stick) sees my system disk as completely unallocated although it has one huge ntfs partition with Windows 8 on it. So I booted into Windows again and used the disk management tool to shrink that partition and create a new one in the free space. I formated that one to fat32. I still got the same behavior in gparted. Does anyone have an idea? My harddisk is a Samsung 830 Series SSD and the mainboard has UEFI. (HowTos)