Try a new pilot or re-starting the mission again.
Theres some problem with the mission briefing I haven't been able to pin.
In the FOw release thread I uploaded a fixed version of the mission, the fix being a removed breifing.
EDIT: The attachement was removed by admin.
There is a fix uploaded on freepsacemods that fixes several mission bugs, can't recall if it includes this (probably not).
If that fix doesn't do it, then removing the briefing should.
EDIT2: Here. Just remove the _nobrief part of the name and copy it in the COTS/data/missions folder
[attachment deleted by ninja]