dedect no partition

hi
i've got a big problem! i have installed 'win xp sp2' on partition "c" and i want to install 'ubuntu' on my empty partition "d".
now i boot from CD and want to install 'ubuntu' on "d" but in the setup 'ubuntu' can't find any partition !?
so i tryed to set a new partition with 'gparted' but this program doesn't find any partition, too !?
what can i do??

Thank you very much!

oRanGe