I'm having a strange problem where the left mouse button doesn't work properly when dragging a window, selecting text, etc. It "releases" either immediately or after at most a couple of seconds even if the mouse button is still physically held down. This seems to happen 100% of the time, although the specific amount of time before release changes.
I've looked through quite a few related questions, but they all seem to be about specific programs. Is there any general reason that this would happen? This is a fairly new Ubuntu installation without too many programs installed.