Remove mouse-detection from a MC

I have movieclip working as button.
On mouserollover it scales up a square MC. The problem is that this square will cover other buttons when completely scaled up, and the buttons below that won’t “work”

See phenomena on http://www.patrickjansen.net/test/test.swf
When going with mouse from button 1 to 3 it works ok, but from 3 to 1 one then the “top-stacked” button will prevent lower buttons from working properly.

I’ve put the .fla + .as to check on http://www.patrickjansen.net/test/test.zip
As you can see I tried
sq.mouseEnabled = false;
sq.mouseChildren = false;
but that doesn’t help

Anybody any idea?
t.i.a.
P