If this option is enabled, scrolling will automatically be converted into zoom (but only in Excel). In this case, you will be able to resolve the issue by accessing your Synaptics driver settings and disabling the feature altogether. If it is, the only fixes are to either unstuck the key or to replace your keyboard with a new one.
If this scenario is applicable, you should use the On-Screen Keyboard to investigate if the Ctrl key is indeed stuck.
