I just wanted to state that I have the same problem on my Atrix (european model). I am running mrom.
My atrix simply cannot write to the internal memory anymore. I can't delete files, I can't flash a ROM, installting a new sbf with rsd lite does not do anything, formatting with CWM does nothing. Every time I reboot the phone it resets its status to that of a certain date. Nothing since the last reboot is saved (call log, SMS, internal photos, apps, etc).
So, a few of us are unlucky enough to have this problem which apparently cannot be fixed?