Hmm. Yea, I've been using v6.1.1 beta 10, so it seems like that could very well be the problem. However, I did as you suggested and got 6.1.9, and it works, but when I check "load hi res textures if possible" it goes through the loading process, then crashes. It names ntdll.dll in the details, if that helps. Not sure what the problem is.
EDIT: Alright, so after swapping some textures around, I figured out that it will load the game fine, but as soon as you're about to see a replaced texture, it crashes. Also, to clarify, all I did to install the plugin was put the "plugin directory" contents in the plugin folder, and the "emulator directory" contents in the pj64 folder. There was no readme in the download, so if there's another part to the installation, I'm unaware of it.
EDIT 2: Alright, so I went down to 6.1.8, then 6.1.6, and finally to 6.1.4 (which is the last one before Aristotle, if I'm not mistaken). 6.1.4 works, AND loads the bigger textures I wanted, so it's all good. Thanks for your help.