Text input trouble on OS X Snow Leopard - text doesn't show up before mouse click
Is it possible that the mouse button is sticky or not clicking properly? This would mean that the cursor could be someplace on screen but the software is trying to follow mouse movements and expects you to click again where you want the text to go. We did have a mouse button on a MacBook Pro that just would not function properly, although the problem was different – you had to pound it to have it register. We ended up with a Bluetooth mouse that works brilliantly.