Go into Task Scheduler and look at all the junk you'll see listed there.
Thinks like Chrome and Adobe and Asus updater will be triggered at logon or during late night, but then run every 60-240 minutes there after.

So edit the "trigger" options to these, and just make them run once during late night, or if you the type of person who switches of your computer, then make them trigger at logon only, removing the repeat every 60 minutes settings.

One or more of these are triggering on a regular basis, and it pops up a quick-flash window that is causing your full screen games to alt-tab.