A quick update on my upgrade woes: I discovered that my "downdate" back to 4.03 had some problems (namely that the animation preview stopped working; the button would click, the timeline would expand to make room for the little animation window, but no preview would show). I finally decided to do a fresh install of Vue to a new folder (to avoid trampling my existing installation, just in case), then upgraded again to 4.03. Oddly enough, same problem with the preview. I tried it again from scratch, this time going to 4.1. Now, rendering kicked in immediately, with no delays, but the whole thing hung on exit. After some thought, I disabled OpenGL, and now everything seems fine (knock on wood-grain material texture). I'm running more tests, but 4.1 from a clean install seems to be working. Stay tuned...