I have successfully isolated the problem to BGT-WeiDU. The current version (1.12) simply does not want to work on my system, even if I install it on its own. The previous version (1.11) does work, but I'm not sure if there's likely to be compatibility problems between mods, or if anything in the BiG World batch file that depends on the current version of BGT-WeiDU. Has anyone successfully done a standard-level BWP v10.3.3 install using BGT-WeiDU v1.11 instead of v1.12? I guess I'll give it a try and see if I can get it to work.