I recently purchased a new MacBook Pro (retina) with Mountain Lion and found that my Maple 12 programs would not run.  So I updated to Maple 16.  Initially all seemed to work well.  But now when i try to open a Maple .mw file, I get the message

"File acm23test.mw could not be found.  Please select a different file."

What has happened and how can I get my programs working again?

DavidR