My facepalm moment was in Orbiter 2006, i was in orbit in the stock Deltaglider and was approaching ISS position to dock.
Whatever i did was throwing me away of ISS, i couldn't understand, it was far from the first time i catched ISS and docked, but this time it seemed impossible.
On the 3d virtual cockpit i seemed to have the MFD correctly configured, but nothing was making any sense when i tried to fight against my relative speed in comparison to ISS position, i was always going away .. away .. away without a care to how i should logically move and i even had to fire my main reactor to try to get back instead of just the RCS.
After half an hour of "dancing" around ISS and being very annoyed without a clue of what was going on, at some point i went into external view and noticed a slight little light ... around the hoover reactor.
Damn, i must have pressed the hoover key with my big fingers without even noticing it.
No wonder nothing was making any sense in this ISS approach ... facepalm