Just off the top of my head, try 2048x2048 or 4096x4096. OpenGL doesn't like non-power-of-two textures. I *think* OpenZone tries to fix those, but I don't remember.
FYI: I've been taking a break from OZ for the past few months, but I haven't forgotten about it. I just need to get my queue clear so I can get back to it
