One of the things that can cause the screen to freeze is when a popup or tooltip is displayed. Unfortunately, those kinds of things happen quite often while moving the mouse or typing with the keyboard, which directly mucks up your input, like making certain keys get pressed for longer than expected (as people here have already mentioned) or mouse clicks turning into long-presses.
I've attached a brief screencast of key-stickiness in action, which happened while typing in a textbox that provided drop-down completions.
Created attachment 368465
Key stickiness
One of the things that can cause the screen to freeze is when a popup or tooltip is displayed. Unfortunately, those kinds of things happen quite often while moving the mouse or typing with the keyboard, which directly mucks up your input, like making certain keys get pressed for longer than expected (as people here have already mentioned) or mouse clicks turning into long-presses.
I've attached a brief screencast of key-stickiness in action, which happened while typing in a textbox that provided drop-down completions.