When the message "Phase 2" the program stopt responding.
Check the "JkDefrag.log" file for more information.
Does / can jkdefrag do any diskerror analysing?
No, JkDefrag does not analyze the disk. If there are errors on disk then Windows will handle them. JkDefrag does not write to the disk by itself, all it does is send "move this file to that location" commands to the Windows defragmentation api.