Just posting to confirm that I too experience this crash when loading Pandora's Box with a recent FS2 Open build: r5020 + glfixes.
Rodo: I tried using the 3.6.9 final FS2 Open build, and it solved the crash, but I got some weird issues in game. For example, the targeting brackets don't properly track ships, and the subspace node in the first mission appears to "move" when I move my ships viewpoint. I suspect this is due to using a 3.6.9 binary with the 3.6.10 mediavps. Did you experience this problem?
Either way, I'll put PB on hold for now until this problem is solved, but if there's anything I can do to help debug this problem, let me know.