[haus]

I haven't seen this on mine. I have seen the occasional reboot-on-its-own (maybe once every 4-6 weeks) but never the phone shutting itself off completely and requiring a battery pull. Sounds like something you installed has a memory leak, maybe? It's not necessarily anything you have installed "on top of WM"...any program can cause bad behavior which remains even if the program is fully exited.

Probably hard-reset-and-start-over time...