Are you running a dev kernel or the stock omfgb... I had the problem originally with the omfgb sbc kernel so i flashed tiamat 4.0.8 no sbc and same deal.
I just thought I'd post since I haven't had this issue in a couple of days. I went in and did a 'wipe battery stats' since I was getting big percentage drops on my battery. Since doing this, I haven't had a reboot.