This is a Macintosh-only question.  If you don't know MacOS 9.2.2,
don't tackle this question.

I recently re-built part of my operating system, and now,
double-clicking on a downloaded file doesn't automatically run StuffIt
Expander, like it used to.  (I wish I could remember exactly what I
rebuilt, and when.)

When I use the "File Exchange" control panel to add a new translation

It gives me the message:

       "The document 'xxx' could not be opened, because the 
       application 'StuffIt' could not be found.  (Could not find 
       a translation extension with appropriate translators.)"  

Doing this should simply expand the file.

When I do a display of the file's attributes, in the "kind" column, it
says "StuffIt document", which is correct.  I do indeed have "StuffIt"
installed, as an alias of "StuffIt Expander."  When I launch that
program, and drop the compressed file onto it, it does indeed expand
it.

When I use the "File Exchange" control panel to add a new translation
for this file, I click on "Add?" and navigate to the ".sit" file that
I had downloaded.  When I click on that file, it gives me the error
message,

       "This file may be opened only by the application that 
       created it.  (You cannot set a translation preference 
       because no translators or alternate applications can 
       open this file.)"

The Apple Support site has the following article similar to this, and
suggests that I delete my "File Exchange Preferences" and rebuild the
desktop.  I did that, to no avail:

http://docs.info.apple.com/article.html?artnum=25332

I found the following user experience that claims the error is
indigenous to StuffIt version 7.0, while version 6.5.1 worked.  His
description matches my experience, but I'm 98% certain I've had
version 7.0 work for me:

http://www.versiontracker.com/dyn/moreinfo/macosx/12012&mode=feedback&vid=47530

Probably in the past I did use version 6.5.1, but unfortunately, I
can't find it anywhere on my backups of my hard-disk.

I've tried this with both Expander 7.0.1 and 7.0.2.  I'm running MacOS
9.2.2 on a PowerMac G4 tower.

I'm at my wit's end.  Help!

--Mark