I'm running SheepShaver 2.5 in macOS Big Sur, and I got it set up and functioning great for a little while, running some games in OS 9 (my main purpose for setting it up in the first place). Then, it crashed, and now it doesn't display a window on launch and automatically crashes. I zapped the PRAM with the script in the folder, no change, and then deleted the prefs and got it to open but of course not boot. I pointed it back to the ROM and hard drive image (OS9.dsk) and it went back to crashing at startup, no window ever displayed. Below is my prefs file contents, but of course it was working with the same prefs I think before (I don't believe I changed anything when it crashed):