Reset Rigid body IPO's

I’ve been playing around the rigid bodies for the first time in the logic panel. I placed a load of cubes and let them drop on to a plane by pressing the p key. I then used the “record game physics to IPO” option to enable me to render the animation.

Now i’d like to to move some of cubes and re do the physics part but when I move a cube and hit p the cube jumps back to its original position. If I delete the IPO curve for that object it then seems to work ok then. So each time I want to redo the pysics after using the “record game physics to IPO” option do I always need to delete all the IPO curves? If so how can I delete all the IPO curves for ALL the objects in one go?