Windows 7: synaptics touchpad zoom too sensitive

Is there a way to disable JUST the "zoom" feature of my Synaptics PS/2 Touchpad? I keep hitting it (I guess; or it's doing it by itself) and inadvertently zooming in or out. I have to go to Chrome zoom control and keep resetting it to 100%, which is a size just fine for most of what I do. I usually have my laptop in my lap, not on a desk, so don't usually have a surface to use a USB mouse. I was able to lower the sensitivity to keep the darn pad from scrolling madly up and down unexpectedly, but can't find anywhere to do the same for the zoom; it's VERY exasperating! (Toshiba Satellite C655-S5540; running Windows 7 Home Premium, 64bit)