I usually "pause" the sim with the "Esc" key - it's been the least disruptive way to hold my place when I need to leave my computer.  Since SU5 I can no longer toggle a pause in this manner.  It usually will pause OK but will no longer toggle back.  The only way I was able to return to the flight was by clicking the Resume button.

On my last flight this really went haywire.  First, every time I returned (unpaused) my throttle dropped to idle and I had to quickly jog the throttle control and reset (I may have found what caused this).  About 1/2 way through the flight the "Esc" key stopped working entirely - I could not pause, go back to option or any other menu.  I had to use Active Pause to hold.

you need to rebind a key command, I don't remember which one.

Funny the ESC key works but the spoilers / does not since the update....