My TED works fine, but sometimes I get the annoying white screen too. If you're sure your SD card is good and you have the region switch on the card in the correct position, I would also try pulling the card out from the slot just a hair (with the system powered off, of course). Then try powering it on again.
Sometimes if you shove the cards too far into the slot, they don't make very good contact with the card slot pins and you'll get a white screen.