just started having this problem with my 4200nex, its like 3 months old, I will be driving then the faceplate/screen starts to restart. it will do it once sometimes multiple times. u can still hear the radio and everything else but the screen just goes black then restarts.

any fix? heard of this before?

I would send it in for warranty if you're sure your wiring is all OK.  The warranty repair is quick, about 8 business day turnaround time for my dads head unit.  His turned out to be a burned out IC.