I have a laptop mouse (love those little things!) but sometimes when the cord is pulled out all the way or is tangled, it does that. Make sure the mouse is pointed properly. It will do that if it is pointed upside down.

Check your scroll-lock key to be sure it isn't on. Make sure the mouse is plugged into the correct port or port-type. You may try re-booting w/o the mouse and then plugging it in again afterwards to be sure it is picking up the correct accessory. I do know there are settings you can change in the Control Panel, can't remember from when I had that problem long ago.

Maybe someone else has some info - good luck!

When mine does that, I know it is time to replace the batteries.

I think you should try to go into the control panel and change your mouse settings. Your computer may not be recognizing an external mouse.

'Make sure the mouse is plugged into the correct port or port-type. You may try re-booting w/o the mouse and then plugging it in again afterwards to be sure it is picking up the correct accessory."

If this is a wired mouse...

---> If it has a round connector, that's a PS2 connector, and the computer must be turned off when it's plugged in. Then turn it on and boot up. Or, if the machine is already on when you plug in a PS2 mouse, you'll have to restart (reboot) it, in order for the mouse to be recognized.

---> If it has a flat, USB connector, it can be plugged into any available USB port; and the machine can be turned on when the mouse is plugged in. USB equipment should be recognized right away when it's plugged in.

As Dilly_Dally said, you probably should go into Control Panel and click on the icon for "Mouse" and make sure all of the settings are correct.

Also, bear in mind that when an external mouse is plugged into a laptop, it doesn't automatically disable the built-in touchpad on the laptop. If your thumb, or shirt sleeve, etc., brushes across the touchpad, that will affect what the pointer does and where it ends up.

I assume it's an optical mouse. Try wiping off the bottom where the light is. Dirt will make it do strange things. And I'd suggest you turn off the touchpad mouse on the computer since you don't use it.

Thanks for all that advice, muchly appreciated. I did clean the light and I turned up the mouse speed. It seems to be a little better.
I don't see how to turn off the keyboard mouse, I'll have to get my computer tech neighbour to show me that. Actually I'd be happy to just turn off the automatic click on it, as that is very annoying.
Thanks again, everyone.
Suzan J

I did not see in your first post that you are talking about an optical mouse and not a corded one.

One thing that can affect an optical mouse it the surface you use it on. Use a mouse pad. A shiny reflective surface can make an optical mouse behave erratically.

After trying my neighbour's mouse we came to the conclusion that the optical eye in mine was dead - took it back to Wally World today and got a new one, which works just great!
Thanks again for all the advice...
Suzan J