pc navigator isnt perfectly(and i use this term loosly) supported till 8/8 version of rr
but i still feel if set up right it will work with 8/1
i see from that load, your using the non free version right?
debug.txt might shead some light
also for window name better as "!MPFCWindow!Navigator"
using the class will help make sure right window does embedd
but not launching, is something in your load command