i am not really Sure What that Option Does But i am sure the persion who Made the SMD installer Will =)
What you can try Doing Is down load My Install CD v3.0 and do a Dash Install and see if that works
http://www.smdepot.net/forum/index.php?topic=1266.0(wfi) error 21 just means Dash can Not be found On boot So the dash is missing Replace it and it should Work