I've noticed the glitch that occurs when minimizing or switching windows, and sometimes during normal work, sketchup will randomly apply my current smooth/soften settings to either the selected object, or if nothing's selected, the whole model. In fact, it's happened to me I think four times today. Sometimes, I catch it in time to undo it, but too often I don't notice it until it's been saved or pushed back too far in the 'undo history'. This is the single, most time costly, annoying glitch I've ever encountered! It can sometimes take another 20% of the time I've already taken to make the model just to fix the edges. (When it gets to my sometimes multi-month-long projects, that's a few very boring/frustrating days!)