When I have the buffers dialog open (list-buffers) if I hold down Alt+D to close a bunch of buffers the Alt+D will "leak" into the buffer that normally has focus, deleting lines (Alt+D is mapped to delete-line).
This happens with other commands too.. after opening various dialogs, I'll have various letters show up in random places in buffers that had focus, and those files show the asterisk near the filename noting a change. If I undo, they clean up fine, but these keystrokes should NOT have gotten there.
This is a common occurrence on Ubuntu - I don't recall having seen it in Windows.