I installed the BeOS and rebooted. Every time I choose the BeOS from the "OS Chooser" extension dialog, I get an error message about "Can't allocate PEF Memory" or "Could not allocate system memory for boot info. This is a memory error. Contact devsupport

This now uncommon problem seems to result from various combinations of extensions conflicting with the OS Chooser. You can try to isolate the problem if you have Conflict Catcher or Now Startup Manager.

Otherwise, disable the OS Chooser extension, and instead launch the BeOS by using the "BeOS Launcher" utility, located in the "BeOS Mac Tools" folder.