Windows 7: Flashing taskbar/windows

So one time i went to change the volume today but whenever i opened it, it would close.

at the same time, the language bar that's integrated onto the task bar would flash.
this goes the same when im trying to close a second window of firefox (when 2 are open)
i click the icon, and move the mouse to click the x, but im too slow and the previews are closed before i can get to the X

at the same time, when windows are open, they flash (like they are switched to, then not switched to) i believe that the flashing/blinking cause the volume/preview menus to be closed quickly.

OH btw, this also happens with the start menu (eg when i was trying to hit "Restart", the start menu closed on me due to the blinking..!)

this was random and after a restart isnt the fix. this happens mainly when changing the volume or doing anything with the taskbar.

anyone know what's wrong?

thanks

help to understand -> VIDEO

this is weird, but after uninstalling League of Legends (a recently installed program), things started working again.