Hi, I already opened a bug report (see bug #706789) but i haven't answers for the moment. So i send this message to know if someone had this problem.
I know that in this page ( http://www.debian.org/devel/debian-installer/errata) a problem with UEFI and Debian installer for AMD64 systems. Explainations about Win7 and Wheezy installation with UEFI mode : 1- I have a laptop bought in summer 2011~ and the UEFI mode is disabled by default. I wanted to install Win7 and Debian Wheezy with UEFI mode for tests and find bug. 2- I enabled UEFI mode in my BIOS, i choose to boot on my DVD drive with UEFI mode and I was able to install without problems Win7 EFI mode. 3- To install Wheezy RC3, i used a USB Key. In the BIOS, i see correctly the UEFI mode for the USB Key and i choose to boot it in the first one. 4- When i boot on the USB key, i have a message which appears during 1s = Error : prefix is not set After this message, the installer main menu appears so i can choose between "Install","Graphic Install", "Expert Install" etc... The problem is here, if i choose one of these options, i have a black screen and i can't install Wheezy. I tried all options for the same result. 5- The only solution to install wheezy is to install it with UEFI mode disabled Thanks, Max