This happens to me fairly often. I'm playing off Desura, so I believe I'm at ver 8.9. The scenario is as follows: 2 F17's (although once they were with a Mig) are sent to intercept a fighter. The air combat initiates, the fighter trying to fly away to the western edge of the screen. The music sounds like it's playing twice, one tune approximately a second behind the other. The edges of the grid (The 7 bottom rows) are much brighter than normal. Initiating afterburners affects nothing. Eventually I hear missiles launching, but no animation. The edges of the screen show the geoscape map, and I'm able to scroll around it, and enter base view, but the majority of the center of the screen is blocked by the air combat. I sometimes hear guns in the soundtrack even when the fighters are out of range ( due to not afterburning).
When the fighter reaches the edge of the screen, the game crashes.