Fist off, Creative Cow forums are amazing. You guys have helped me with numerous issues in After FX and Final Cut, and I thank you.
So here's my new issue: I was working on a mask in Photoshop CS4 and I think I hit a shortcut accidentally, because all of a sudden my eraser and brush were doing the opposite of what they were supposed to do - namely, the eraser was revealing the layer source and the bush was hiding it. Prior to this mysterious shortcut, the eraser was hiding the layer and the brush was revealing it (like they are supposed to). I've poked around the preferences and relevant menus but I can't seem to find anything. Anyone know what's going on?