Yes a corrupted scene is the original problem, and removing the unused material groups is what we would like to do. There is another thread where solutions were offered.
http://www.renderosity.com/mod/forumpro/showthread.php?thread_id=2795447

The long texture list is another concern, and while sometimes you may want all of those textures available in the list, other times you don't. There is no option to clear them out.

Sometimes I'm not exactly clear so apologies if I'm not getting through.