I asked the same question the other day and someone mentioned that this is a known issue with the .340 update, so I'm not sure if there's anything we can do about it. One option was to install an app called "No Lock" which gets rid of the lock screen, which will minimize the chance of a reboot.
It happened to me with .15 on black glass theme. Still happened after I sbf'd back, ungraded to 340, after reroot. It stopped after I rom'd to darkslide.