Firstly what an awesome game even with bugs
Anyway, not sure if the bug has been reported.
I managed to get my chinhook 1 and interceptor 1 to both engage at the same time.
The first pop up was for the interceptor to engage a small UFO, the game then froze with the chinhook engage screen showing on the geoscape.
I would have attached my dump file in .zip format but getting 404 error when I click manage attachments.