I've a got a C# app with a few buttons.
Hit the button, get a box to confirm some activity.
But sometimes the box would not pop up.
Maybe sometimes would pop up in a blink, other times, it seemed like forever.
Again, and again.
Was the wierdest thing.

And then I realized.

The mouse needed to move.

But I'm using a track ball. So it is very easy for me to press the button without any mouse movement at all.

I'll bet someone with a mouse could NEVER trigger this bug since the act of releasing the button would move the mouse.