I'm having the weirdest issue and it's been happening on and off for like a year now. It comes and goes as it pleases, seemingly.

Basically, applications will become inactive randomly. Here are some examples: While playing Call of Duty the mouse will pop out of the game. The keyboard still works inside the game for some reason, but the mouse will hover ontop of the window until I click anywhere in the game.

This has also happened while playing Minecraft, or even working in Zbrush. I've been typing before and suddenly the field is just unselected, then sometimes reselected. I currently don't have any extra modes of input plugged in like game peripherals, it's just my mouse and keyboard.

An even more basic example is if I click on my desktop and drag around, the blue selection box will sometimes unselect and reselect.

The really frustrating thing here is how inconsistent it is. I cannot replicate it no matter how hard I try. I've switched my mouse but in the course of typing this the window unselected itself then reselected itself. I don't even know what to tag this as because it's so bizarre. But I feel like it's software based so I'm going with that.

The way it behaves it's almost like another program in the background is very quickly becoming active then returning the active window back to what I was using, if that's possible. In the case of Zbrush that would make this look like my mouse is simply unselecting mid-click, since it resumes the click a fraction of a second later, yet programs like COD I have to click back into the window.

EDIT: I do want to note that I have a logitech mouse, and I'm aware of the double click issue. But that issue isn't happening here. It has no correlation to double clicking at all, as double clicking would simply fire my gun twice in COD, not bring the mouse out of the game. I've also tried to replicate this to no avail. Like I said before, I switched mice and still have the issue.