I CSOCSO!
You only have to delete the rgnfs.dat file before creating your bsz skin, or simply when asked to create bsz, uncheck the rgn.dat and the rgnfs.dat files from the list.
Those files are created to remember the skin shape and to load more easily the skin evrey time you load BSplayer. But if you change the skin and don't delete those files, then a wrong shape is remembered, and the resulting skin get corrupted.
Delete those files every time you change the skin shape, also if you don't compress the skin in bsz format and want to leave it in its folder
