PS/2 Mouse problem

So I bought a ps/2-to-usb adapter cable so I can use my old mouse and keyboard that I've had for 10 years.  They're both logitech by the way.  Anyway, the mouse works great with my laptop using the adapter cable no problem.  So then I thought I'd try it out on my brother's all-in-one desktop.  I plugged both the keyboard and mouse that both use ps/2 into the adapter cable.  And the adapter cable into the usb port in the back of the computer.  The keyboard is working great with no problems.  The mouse however not so well.  It lights up and I can move it across the screen but its all over the place.  I just need some help troubleshooting this.  

Nevermind, I fixed it.  I got rid of the mouse pad and its working perfectly lol.