MrRon, the same problem for me, on my notebook with Seven Ultimate 64 Bit and Defraggler 64 Bit : by "analyzing" my external firewire disk Maxtor 160 GB (named X:) Defraggler stops at 32%, and the debug output file says that the disk X: was correctly initialized, but the "redirection of Wow64" failed. Defragmenting the internal disks C: and D: works properly, instead.
Thanks you for your suggestions.