I’ll be honest, I don’t think you picked up a virus that did this. Sounds like a glitch somewhere along the way. Of course, step 1 is to always reboot. Step 2 would be to ensure your Scroll Lock key on your keyboard is off (press it once).
The fact that you have to right click X makes me think something is messed with your mouse - did you try unplugging it and plugging it into a different USB port?
I tend to agree with the glich as being most likely.
But if it’s a macro that is misbehaving, try setting your macro security to high. Close and reopen and that should disable any macros.
I’m not sure about Excel 97 but Office 2000 and later versions have an Office diagnose and repair tool that you can find in your start menu under Microsoft Office.