In case anyone else has this problem, I solved it myself. The problem was a typo in the file patch to the tmp folder. Who knows how it got there. I don't think I would have typed it in manually when I built the site almost four years ago. I guess check the path for EXACT precision, or you will get an error.
Joomla uses the TMP folder as a launching pad for zipped applications.
The funny thing is, I've installed or updated several apps recently, and Hikashop was the only one that gave the system fits.
-Jim Gribble