Can't Turn Off Mouse Keys Type Activity

I know Mouse Keys allows the numeric keypad to control movement of the mouse on screen. I've checked this setting on my computer and it is turned off - which is my preference. However, when I press Alt and any of the arrow keys, my mouse moves across the screen. Alt-Up moves the mouse pointer up, Alt Left move the mouse left, etc. This interferes with other programs on my laptop. Is there some other setting or program that causes this? If so, how do I turn it off?

This is a recent occurrence. I've been using Windows 10 for a while and this has not happened before. I have not installed anything recently that would effect the mouse. I am using a Logitech MX Revolution mouse, which has it's own control panel settings. But, it has no function for moving the mouse using the keyboard. I've checked the Windows mouse and keyboard control panels too and have found nothing to stop this from occurring.

Does anyone have any insight? I'm running Windows 10 x64, on an HP Envy, with an i7 processor.

TIA for any help.

You may have a stuck key on your keyboard. Turn the keyboard upside down and shake it and blow it out with a can of compressed air. Try the Onscreen keyboard. Try a different USB keyboard.

Using the onscreen keyboard or USB keyboard isn't the solution, it is to test if it is a software issue or if it is the keyboard itself. If it is the keyboard, it may need to be replaced.