I am on my 2nd "certified used" replacement of my original Droid 4 within 2 months. My phone, once from low battery shut off and then for no reason will occasionally shut down/restart... once the restart happens, it will not finish and continue to shutdown and restart, over and over again (power cycling)...I have done normal reboots ( holding down power and volume at same time) as well as factory resets.
I have had a number of different apps on the phone, this happened prior to me installing Go Launher/Go SMS... I previously had Handcent. The one thing I do have is a large # of apps in "All" and "installed"...