Well, I've got the Particle Editor working for everything except "geo_sfx_weap_blunderbuss_ord.fx", and that's the one I need to edit at the moment. I didn't do anything different than I've done previously, so I'm absolutely clueless. I have done a search (for the relatively uncommon word "blunderbuss"), but I didn't find anything. Any help is appreciated, so thanks in advance.

If you're running it out of your GameData\Data\_LVL_PC, it's probably missing some of the munged files it needs to open it (I assume PE just crashes?). If that's the case, all you need to do is munge the effects folder with those files you need in it, go to your modmap's (this doesn't need to be any specific modmap) BUILD folder, and find the right config.reqs and model.reqs and copy them into your GameData\Data\_LVL_PC\munged folder.

Here's a similar topic:
http://www.gametoast.com/viewtopic.php?f=27&t=15267

Dang...well, thanks for that! I've got it working.