Update: The bug is fixed in 220.127.116.11 - please make absolutely sure you're running this version or later before partitioning your card. As posted here on XDA, it seems that the current clockwork recovery build, 18.104.22.168, will brick your phone if you use it to partition the sdcard. It seems that the partitioning tool is getting confused and formatting some part of the phone's internal memory, turning it into an expensive paperweight. So far the only solution is to send it back to HTC and play dumb. I'll update this once a fix is out, but for now, please just partition the cards manually via your computer if needs be.