What causes strange mouse behavior when clicking, dragging, etc., Windows 7?

Question

User interface

W7 Desktop. If you grab the slider and drag it outside the scroll track, for a while the slider changes its location correctly, but after some time (it happens without pauses), it goes to another active area (desktop, for example) and a click with a press or a release is already triggered there keys. When you drag the window, it suddenly flies off and other events are triggered along the trajectory of the movement. Focus does not work, sometimes you need to double-click. The mouse is wired standard, it is not always possible to reproduce all miracles. I sin on updates (support for touch-screens). Possible infection (but unlikely).