Well, I didn't obey that excellent advice from Charles. I installed the 10.5.5 update. Now DS9 - in my opinion, one of the heartiest and most reliable programs I've dealt with in the astronomy world - won't work because TCL is broken. I doubt TUI or most of the other things I use will work either. That's a tragedy of significant proportions - I NEED ds9 to make my observing files! I can only pray that an update of TCL using port will work... if not I'm basically screwed.