Unetbootin is running on Windows Vista.
The freeze occurs just as XMGR loads during DOS boot.
I have also observed another problem introduced by 419. The IBM PC-DOS 7.10 RAMDisk utility crashes the FreeDOS kernel where previously in 408 it did not.
Presumably these are related problems, as they both involve low-level memory handling.
Example boot disk: http://superkeen.com/peacecorpsfiles/FUZOMA12.IMG