How Can My Mouse Move by Itself After Windows Starts?

After Windows starts, I sometimes notice that my mouse pointer begins moving by itself across the screen, even though I am not touching the mouse, and the movement can happen randomly within a few minutes of reaching the desktop. I have already checked the mouse connection and restarted the computer, but the strange behavior occasionally returns, making me wonder whether a driver, startup program, Windows setting, remote access service, or background process could be controlling the pointer, and I would like to find out what might be causing it and how to troubleshoot it safely.