That is what I think is causing your problems; the mouse driver. Try to reinstall your mouse driver.

Do you have your mouse on a rollout keyboard tray under you desk? I find that these can cause more headaches than they prevent. The mouse/keyboard cables always get caught in the retract device and eventually wear under the outer coating, causing similar problems. I always recommend wireless when you have a pullout keyboard tray.

Hope this helps, feel free to post back for more advice if it does not.