daddog, I was having this same problem.
If your Aces High files are NOT installed in the usual C:/Program Files/whatever folder, then what you need to do is to copy the path of where they actually are installed.
Then, use a text editor (I use Notepad because it's easy and it works) to open up the ".mis" file. Scroll down until you see an "EVENTS" bit, and you'll see there's a file path under that (which will be the default path for where Aces High is installed). Then, open up the "Replace" thing, and type in the first few bits of that file path you just found, and then replace it with the appropriate bits of YOUR AHII installation. Once you've done that for the whole file, just save, close, and it should all work.
Hope this helps, sorry if it's a bit long-winded.
<S>
Yossarian