On a couple occasions recently my SL500 has lost power. The car appears to have gone into some sort of 'Limp Home' function. I was able to drive the car up to a max speed of about 20 mph.On both occasions the roof was folded away and unfortunately due to the glare of the sun I couldn't see whether there was any message on the dash. I can't find any reference to this in the owners manual. Can someone please suggest what this might be, and what the remedy might be. Thanks very much.