Since installing Lion (clean install) disk utility doesnt finish erasing or partitioning external disks. I used the disk utility from the install drive to erase the internal drive before installing Lion, this worked fine, but ever since it failed to erase any of my external drives. It starts of as normal but the progress bar stops half way and just never finish. However, Disk Utility does respond. I tried different format options, repair and verify but none of the processes finish. I went back to the install drive that I used to erase the internal drive before Lion install and it also didnt work. I copied the old disk utility from Snow Leopard to my desktop, it opens with a warning, but gives the same outcome. Reinstalled Lion, but the problem persists. Any advice?