I found the solution tonight for my problem with this. It's actually a bunch of problems all rolled together.
- Alt-Tab does not work. It flashes up and disappears.
- Can not Highlight any text using the mouse
- Can not Click on a task bar icon and select from list of grouped window previews
- Volume control slider keeps going down to zero by itself
I have a fancy Dell keyboard, model SK-8135, with a bunch of "media control buttons" along the top of the keyboard... including a rotary volume control knob that I never use. After rotating the volume knob a couple of clicks, the problems stop...... the
volume control stops moving by itself, Alt-Tab works again, I can highlight text again, and I can select grouped windows from the task bar.
If anyone else has this problem, I recommend you examine the front of your computer and your keyboard and mouse devices for "volume up/down/mute" buttons (laptops often have these above the keyboard) as well as any additional buttons that open email or calculator
or something
Go along and press each one of these keys a couple times, to "exercise" them. It is possible that one of them is stuck in the pressed or active state, and so it is sending a continuous stream of "keypresses" to your computer.
(It would be useful if there were a diagnostic tool that can report all "keypress data" being sent to the computer from any device, but I am not aware of anything like that.)