Solution
<Phenomenon>
In the Mac OS X Lion (10.7) environment, when scanning using the operation panel of the main unit continuously, as MP Navigator is not launched, scanning cannot be performed (no response even after pushing the button).
<Solution>
Download the special tool (MP Navigator EX X.X Opener) from the download site to install it.
REFERENCE
For how to use the tool, see the procedure in the downloaded file.