Every time a new major version of Aces High is released, we have learned to wait a month or two before a corresponding, new version of the Mission Editor is released. Your problem is probably related to that.
However, I just tested two old versions of the Mission Editor, and neither of them "hung" as you described. Perhaps this is because I also retained the corresponding old versions of the Aces High "front-end". I don't know... but maybe that's why my experience is less disruptive than yours.
I find I can always use old versions of the Mission Editor as long as it's resident in the same "folder" with the corresponding Aces High "front-end" files. This allows me to continue editing during these "between releases" periods. Later, when the newer editor is released, I'll test anything I developed during the interim. Sometimes it's easy to make a mission work with both an older version and with a later one. Sometimes it's really painful, so I don't always do it.
I suspect that you don't have the filesystem arrangement that I described. Is that correct?
Related information about an older version of the Mission Editor can be found here:
http://askmisterwizard.com/phpBB/viewtopic.php?f=11&t=12280And information about installing multiple copies of Aces High can be found here:
http://askmisterwizard.com/phpBB/viewtopic.php?f=11&t=912Regards,