should work even with collision detection "on"...anything unusual about the window?
check for a bad wall construct and/or replace the wall
try using menu/file/repair
maybe the window does not really fit...if it is close on the sides or top or bottom
insert a smaller window and then change its size to bigger as needed
make another wall elsewhere as a test and try window there to see if its a wall or window problem...delete when done
suggest you post the .bld file for people here to have a look see to find a problem as windows usually work just fine
