Are you using headphones? If so what are they hooked up to? It could be that one of the contacts is not hitting correctly so you only get one side. Being that the left is contacting and the right is not so left would have volume and right would not.
Another thought is are you connected to a stereo source? We know that on everything for outputs left is mono and right adds stereo. So I'm wondering if you perhaps have a mono plug instead of a stereo plug. Or something like that is going on so even if you hear it in both sides of the headphones there is only contact to one side and not the other so panning would have an effect like this.Maybe a bad set of headphones or bad connection, Do you hear both the left and right channels or only left?
Also if you Hover over a button and wait a second the shortcut dialogue will appear. Record is (Number Pad) * (star)