mouse moves vertically but not horizontally

I'm having several isses with the PC but trouble shooting is not helped by this. I also have 100%cpu usage - and although I ran msconfig and deslected all programs they are still running at startup?

Hi and Welcome to WhattheTech.

Did you test the mouse on other computer to check if it is still working properly?

I ran msconfig and deslected all programs they are still running at startup?

Msconfig is not a good way to manage your startup applications.

The System Configuration utility helps you find problems with your Windows XP configuration. It does not manage the programs that run when Windows starts.

Quoted from here

You say you have 100% cpu usage. Is this true all the time? If so I think you have an infection and I suggest you to post a new topic in our Infections Removal and our Malware Experts will help you out.

As well as the above, if this is a balled mouse it could be crud on the rollers, open the underside to remove the ball, then gently but firmly remove the build up on the various rollers in there, try and ensure the crud is removed from inside the housing, and if you blow to remove stuff keep your eyes closed, trust me lol, been caught too many times there, when the rollers are clean put the mouse together and see how you go, but you may have other issues as well as suggested above, so lets see if this sorts the mouse before moving on, but another test is plug in another mouse, if that works then it's your mouse, and hopefully this will sort that, but if you replace it then optical mice and the like eliminate this problem.