What kind of computer are you using? Laptop or desktop? Make and model? Operating system running on the system? Have you run any scans for malware? Used any registry scanners or "optimizers" which can frequently cause the issue you're seeing?

IN the meantime, you can try using a different mouse to see if that helps.. And generally, pressing Alt+F4 (at the same time) will close the active window on the computer.

Hope this helps.