To top everything off, when I try to build my level as one large level of blocks (as opposed to "chunks" of entities from separate builds of pieces of the level), at the very end I get a "Map Compiler has encountered an error and will have to close. Send Error report?" message. This happens consistently, it happens in 6.4 and 6.5, and happens even after I uninstalled and re-installed GS, checked for viruses, etc. I should mention that it only seems to happen when I try to build the level with all blocks set to "detail" and/or "passable" in an attempt to speed up the build (otherwise it takes forever). It seems to get to the very very end of compiling after running through the various loops of calculating nexus, portals, intersecting detail blocks, etc, many times, and then it gives the error listed above. I really have no idea what to do next. I think I'll try compiling the entity "chunks" with detail" and "passable" set for each, then compile as one huge level of entities and see if that makes any difference at all. Suggestions would be welcome...