When a mouse scrolls randomly in the opposite direction, it is mostly due to outdated mouse drivers, a low battery in wireless models, dirt around the scroll wheel, software conflicts, or wrong system settings. Besides, some mice can wear out their scroll wheel sensors over time. Cleaning the wheel, reconnecting the mouse, updating drivers, verifying scrolling settings, or using the mouse on another computer are some troubleshooting steps. If the problem persists, you might consider repairing or replacing the hardware.