I've been using photoshop for years and in the last month, I can no longer grab an element and drag it to a new place on a layer. I can move it with the arrow keys (which takes forever) or I can turn on free transform and move it, but when I just try to grab and drag the element (any kind of element) it just snaps back to its original position. I'm sure it is something I've done, but I don't know how to undo it. Nothing is checked in the Snap to menu and Snap is also not checked. The layers are not locked in any way I can see. I'm using photoshop CS5 Extended version 12.1 on a Mac Pro with plenty of memory. I've tried restarting and it still does it. Any suggestions?