What is knocking video player out of full screen?

[impmon2]

This happened with WMP, Classics, and VLC. Once in a while, something would knock these video player out of full screen but nothing comes up like a prompt or alert to explain it. I've had this happen even when I've disabled wifi (it's not connected wired at all) It still happens even when Windows is fully up to date. It gets annoying that I need to reset full screen mode to continue watching my video.

Windows 7. Since no error message came up, I can't tell what offending program is trying to steal focus. I've used Avast, Spybot, and Malwarebyte and there's nothing known on my computer that doesn't belong there. Is there some way for me to look at list of apps that popped up in the background, maybe to check for update and interrupting my video experience even when it's not online? Taskmanager doesn't show anything but the offending app may have quit before I could check.

[Baldrick]

Tried disable screen savers and any power save functions? But they shouldn't cause full screen changes....

[impmon2]

No screensaver. When it's plugged into power, the screen dims after a few minutes of inactivity, that is all. Since the screen doesn't dim while playing video, I don't think that's it. Plus the change can come after many minutes or even an hour of video, that is outside any of power saving feature (sleep in 5, shut down in 30 when on battery)

[jagabo]

There's probably some program running in the System Tray that updates it's little icon. Or otherwise running in the background and thinks it needs grab the system's attention.

[impmon2]

It's taken me a while with IP sniffing, every single time my player got knocked out, there was some traffic to Adobe. I blacklisted everything about Adobe in HOST file since I don't have any product (no flash, no reader, etc) and it still tries to connect, knocking the player out of full screen.

There was some hidden setting in task manager that I found and deleted it.

Seems asinine that a major corporation can't code their software to be a little more discreet about checking for updates or that it kept checking long after I threw out flash player.

[Krispy Kritter]

Most software uninstallers don't get everything. I started using Revo Uninstaller, which often finds additional bits after the normal uninstaller is finished.