Reading your debug log, your GPU has maximum texture resolution of 2048^2, which means you should probably try JeffVader's resized textures.
If that doesn't work, you'll need to use a debug filter; simply create an empty file named "debug_filter.cfg" in ..\freespace2\data\ and then run debug again. But if the resized textures fix the problem, then it won't be necessary to use a debug filter.
Those damn planets occasionally come back to haunt me it seems. In retrospect there are a few things I would do differently these days.

EDIT: And it seems that already fixed the problem. Great.
