The main error is that when you return to "Game Level4" the second time, your variables are not reset. "Level" variable still contains value 4, so event #31 changes layout back to "Screen 5".
To tell you the truth, I don't understand what's going on in your game, all these layouts constantly changing.
Screen 5 goes to Level 4, Level 4 goes to Level 2, Level 2 to Level 3, then back to Screen 5, then back to Level 4...
There's probably some logic to it, but I don't get it.
Try adding "Set Level=1" at the start of Screen 5 layout. Maybe it will help, but I don't know if this can break something else in your game.