I'm attempting to run Basilisk II build 20091004 on OSX 10.4. The settings are mostly the defaults: Mac IIci, 68030 with FPU, ROM file 368CADFE (the IIci stock ROM), 8MB RAM, 640x480, run in window at 10 Hz. No volumes are mounted, I'm expecting to see a flashing question mark.
When I click Start from the GUI window, the Basilisk II window appears and shows a gray halftone background, but nothing further. No sounds, no mouse cursor. Activity Monitor shows BasiliskIIGUI is frozen and BasiliskII itself using 96 percent of CPU.
I also tried Basilisk II "Nigel's port" 19b, which is from 2006 and has a different preference GUI with a couple of options not present in 20091004. I set the window depth to 8 bits. When starting the emulator, this also shows a gray screen with nothing happening. This version has a frame/sec slider, and I'm not sure if this is the window refresh rate or the emulation speed, but I set it to the maximum of 60.