@dean:
in makefile and makefile.multiman there are lines like
@$(MAKE_SELF_NPDRM) ./objs/$(MM_REL)_BOOT.elf $(RELEASE)$(NPDRM)/USRDIR/EBOOT.BIN $(CONTENT_ID) > nul
the >nul at the end of these lines should be >/dev/null
otherwise a file named nul will be created that can't be deleted from windows side (luckily it can be deleted from cygwin shell)

