What type of mouse is it (AT, PS/2 or USB)? And do you know what make it is e.g. Intellimouse?
Have you tried looking in Control Panel / Mouse to see if it gives you a hint?
To start with, I would check all the connections for the mouse and make sure they are secure and in the right socket, then make sure the mouse is clean internally on the rollers and ball. By the sound of it, your mouse came with specific software, uninstall then reinstall it and make sure the mouse is actually using the software and not Windows own version.
Incidentally it may be helpful if you could say what the "gibberish" is. Especially if it gives any code numbers