Your double-click settings might need adjusting.
Click
Make the
Use the nearby lightbulb picture to test whether the mouse is clicking properly. Clicking it once should make the bulb glow dimly; double-clicking should make it glow brightly.
If the problem remains even though you have increased the double-click timeout, your mouse may be faulty. Try plugging a different mouse into your computer and see if that works properly. Alternatively, plug your mouse into a different computer and see if it still has the same problem.