> On a Mac without SD4, it errors. On a Mac with SD4, it opens, then opens  and
starts debugging. I can run the script just fine from  the execute command in
SD4, but no other way.

Levon, I'd try two things.

Open the script in Script Debugger, then disable Debugging from the script
menu. Then do a "Save As".

That may fix it.  What may have been happening is when you save a script
from Script Debugger it activates a live debugging environment to help you
debug a script by dropping files on its Icon or double clicking on it.

If that doesn't work, open the script in script debugger, select all, copy
the script, then open a new script window in Script Editor, paste your
script and do a save as.

If neither of those work, let us know and we'll.

HTH,

ES