I was trying to add permissions to our Admin role for a new module that was enabled. All other permissions were checked prior to this new module.

If I manually checked the permissions, I received the error "An illegal choice has been detected. Please contact the site administrator."

I then used the Reset Permissions fieldset options to Grant All permissions for my 1 module to the Admin role. This worked fine.

Does "permissions_reset" inadvertently not allow you to use the standard checkboxes?