Unexpected Extra MIDI Signals

When I use my Yamaha MOX6 as a controller to play a VST instrument in Cubase, I can play a scale on the Yamaha, and in addition to sending note commands to the VST instrument, some of the keys also send Windows commands to Cubase. Windows open as if I had opened them through the Cubase UI. This makes it impossible to use my keyboard with Cubase (which is what I bought it for).

Is there a configuration setting - either in the MOX6, or in Cubase, that I need to edit to fix this problem?