Scrolling in Safari stops working

I recently got my first Mac, and so far it's working pretty well but scrolling will frequently stop working in Safari. It doesn't appear to be a hardware issue because scrolling will still work in other apps and Safari starts working again after I quit and restart. Everything else in Safari remains responsive but I just can't scroll with gestures or by grabbing the scroll bar.

Has anyone else experienced this? My unfamiliarity with Macs leaves me with no idea where to start looking for solutions.