First, I should thank the people of HLP for the many countless hours of enjoyment I have had because of your work.
Onto the bug, there seems to be an issue from 'M-24 Stage 1' on wards where my screen will turn black except for the HUD (the shield allocation icons that flank the radar are overlapping and located in the default HUD element position, top left). Also, although sound effects from firing weapons, afterburners and switching targets still plays, distance and velocities of target are displayed as 0. This bug will usually come up around 2 minutes into the missions post 'M-24 Stage 1'.
Because this error did not show up prior to this mission yet show up in all missions following, I found it quite likely it was somehow related to the new missile introduced, 'dragonslave'. Therefore I proceeded to remove this missile from both my own and my wingmates' loadouts and, sure enough, the black screen did not occur and I could play out stage 1. However, in 'M-25 Stage 2', the allied hard light squadron carries these missiles and therefore the error seems to occur in the presence of any 'dragonslave' missile, not just player mounted. Furthermore copying over table data of the 'dragonslave' to replace a commonplace missile such as the 'dart' leads to the black screen appearing in all missions with the missile in play. Conversely, overwriting the table data of the 'dragonslave' with another missile seems to remove this bug.
Upon searching the forums, there seems to be a similar, recent issue in Dimensional Eclipse http://www.hard-light.net/forums/index.php?topic=80655.msg1606129#msg1606129
where it was said to likely be caused by a divide by zero.
I hope this information helps in solving a potential bug. ^^