You run out of space on your desk before the mouse pointer on the screen reaches your destination.
You started your mouse move too near the edge of your desk or too near the stack of books and papers in the middle of your desk.
Lift the mouse off the desk and move it back to the center of the desk. The pointer won't move until you put the mouse back on the table and move it.
Mouse won't respond. You've already checked to make sure it's plugged in and that the application is designed for use with a mouse.
Mouse port is turned off in the Control Panel.
Change slot 4 from Your Card to Mouse Port in the Slots section of The Control Panel.
The mouse movements are jerky.
The ball on the bottom of the mouse is probably grimy.
Clean the mouse ball according to the directions that follow.
Appendix B: Troubleshooting