Hello,
One of the most common causes that will trigger this kind of behavior is a stuck CTRL-key. If you didn't know, if you press any of the CTRL keys and scroll upwards or downwards, the mouse's scroll will produce zooming.
Testing for stuck CTRL key:
You should use the On-Screen Keyboard to investigate if the Ctrl key is indeed stuck. If it is, the only fixes are to either unstuck the key or to replace your keyboard with a new one.
Second option: Accesse the Properties for Synaptics screen and disable the Pinch to Zoom:
Change mouse settings -> Once you’re inside the Mouse Properties menu, select the Device Settings. Then, click on the Options button to open up the specific Synaptics settings.
After you manage to get inside the Properties for Synaptics screen, select the Pinch Zoom section from the left pane, then move to the right pane and untick the box associated with Enable Pinch Zoom.
*Restart your computer and see if the issue is resolved at the next system startup
There is another advanced feature that might cause the issue
called “Zoom on Roll with Intellimouse”. Try to disable Zoom on Roll with Intellimouse.
I hope this will help you!
Regards,