I started with a Dell D630 with XP on it. I did a i386 install of F18 beta and reclaimed all the space (deleted existing partitions), auto-partition, with encryption. Installation went fine. On the same computer, I went to install x64 F18 beta with an encrypted partition. In my first attempt to manually set up the partitions on the 64-bit install, I entered the pass phrase to edit the existing partitions. When I went to write the configuration to disk (unchanged because I did not understand the new interface due to lack of coffee), I entered the same pass phrase I had originally used and then the installer crashed. The second attempt after rebooting, I simply selected to delete the existing partitions to reclaim them and it locked up (mouse still worked, I could switch VCs). I ended up going into fdisk to manually delete the partitions, rebooting, and then everything worked fine.