We've released a new build of the MHT plugin which allows it to handle MHT files created by Word 2003 (which were previously not supported and returned a "File format error" message in the Log).
You can download the updated MHT plugin from here:
http://www.wrensoft.com/zoom/plugins.html
You can download the updated MHT plugin from here:
http://www.wrensoft.com/zoom/plugins.html