I somehow got frog blast to run twice. Closing the tab only killed one of them, and I got a "the following pages are non-responsive: Kill/Wait" dialogue with

I somehow got frog blast to run twice. Closing the tab only killed one of them, and I got a "the following pages are non-responsive: Kill/Wait" dialogue with no pages listed. When I chose wait, it still tied up one CPU. When I chose Kill it killed the rogue mystery process