Not that this will happen too often, but it might point to a "memory/resource" issue.
if you open a project, then within the environment open another "recent" project, then open the first, now "recent" project, then open the other...after a couple of iterations, B4a blows up with a memory issue.
if you open a project, then within the environment open another "recent" project, then open the first, now "recent" project, then open the other...after a couple of iterations, B4a blows up with a memory issue.