Date: Dec 3, 2012 3:30 AM
Author: James Stein
Subject: Unfortunate Side Effect of Upgrading to Mathematica v9 on Macintosh

I upgraded from v8 to v9 this morning, and all
pre-existing Mathematica Notebook files (extension .nb) have been modified
to open with the AppleScript editor.

This is easily remedied by applying the "Get Info" command on one of the
notebooks; changing the "Open With:" item from "AppleScript Editor" to
"Mathematica", and clicking the "Change All" button to effect the change
for all notebook files --- but this has the nasty side effect of changing
the modification date of all your notebook files to the current date&time!

This is unfortunate because notebooks in a given folder can no longer be
compared by age.

I hope I made some error and this does not happen to others.....

If others wish to do this, you might wish to do this on a folder-by-folder
basis: Select all the notebooks in a folder, press the option key along
with the command key and you will get a single Get Info window for all your
selected notebooks; this allows you to make the change for several
notebooks at a time, but not all notebooks on your computer.

For those who have little or no use for the AppleScript editor, perhaps a
different solution is to replace the AppleScript Editor application with an
alias to the Mathematica application. I haven't tried this yet....

There may be utilities that allow you to change the "Open With" information
without changing the file dates. I haven't searched for them yet.