The problem is now resolved, and I think I now understand the cause and the "solution."
Installation of Mathematica v9 removed the v8 application. This "broke" the existing linkage between (many thousands) of Mathematica notebook files and their "creator" application. I suspect that the Finder, whenever displaying these notebook files, replaced the old linkage with something expedient.
The problem was still visible and active around midnight of the day v9 was installed. To my surprise, the problem had vanished when I began using the computer the next morning. I expect that during periods of inactivity, system software "goes around cleaning things up."
Anyway, problem now gone.
On Fri, Nov 30, 2012 at 2:56 AM, James Stein <firstname.lastname@example.org> wrote:
> > Possible good news: > The issue I reported earlier may only affect OX X 10.6.8 and earlier; > otherwise Wolfram would have found the bug. > > Bad news: > Even if the incorrect application-creator of a notebook is changed by > hand, so the clicking on the notebook will open it in Mathematica v9 > (instead of the AppleScript Editor), when the notebook is modified by > Mathmatica and saved, it is saved as an AppleSriipt Editor text file. > > For those of us running pre-Lion Mac OS X (of necessity), this is * > unworkable*. > > -- James > > > On Thu, Nov 29, 2012 at 12:05 PM, James Stein <email@example.com> wrote: > > > 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. > > > > > > >