So I take that back. There is another thread where someone has exactly the same key binding and is getting exactly the same crashes:
I was able to reproduce the error by repeatedly pressing “Add label at playback position,” which for me is a custom shortcut key (F1).
I know it has been a while, but if you are still getting these crashes can you try changing your mouse binding to Cltr+M without the Enter or just use Ctrl+M to see if that helps?