I am not using an sd card and I have resorted to the generic kernel when doing any large copy/uncompress such as decompressing one of the linux images (easy debian fedora etc). My phone has rebooted using the overclock (lv 250 850) and the stock kernel. It had no issues on pr 1.2, and I did have a few people chime in on the "boot ubuntu fedora debian" thread (or something of that nature) saying they have had issues on 1.3 with rebooting as well.