I'm using windows 8 here. I tried 8.1 preview and went back to 8.0 because of a performance hit I noticed and my raid array going to sleep. I haven't tried 8.1 official release and I'm not keen because they didn't fix the start menu the way I wanted it.

Not sure what app menu you're referring to that pops up at random. I know if I accidentally hit the windows button it pops up. I have updates set to manual.

I'll be sticking with windows 8 because I'm not willing to pay for another windows 7 license.