Kerbal Space Program

Hello,
I'm new to KSP. I was finishing the Go For Orbit tutorial, trying to return to Kerbin with Valentina as Gene suggested, and when I was clicking around in menus while waiting for a good retrograde burn time, the purple "staging disabled" light turned on and would not turn off. I watched helplessly as Valentina splashed nose first into the ocean, with Gene chiding me. The Abort sequence could not be activated, as backspace nor the HUD button worked. The chute did not automatically open either, as it was not safe to deploy, and I was out of fuel at that point.
I suspect it was opening the "Docking Mode" HUD that caused this issue. Perhaps there is a way to turn off Gene disabling staging after a certain point. As I recall I had left the last window with the "Finish" button open with his instructions.
I hope this is helpful!
-SmashedFinger