My problem started yesterday, January 21, 2017...."Unfortunately, the process com.android.systemmui has stopped. Clearing the cache partition did not help. I found the problem: an update of Google App...both on my Galaxy S3 and my Tablet 2 10.1. I went into Application Manager on both devices and removed the update...which deleted the Google App and went back to the factory setting. Walla...problem solved. By coincidence, this solved another issue I had on my cellphone for months. When I would do a Google search, I lost the sound. That issue has been resolved. The Google App is junk...get rid of it!
Yes, the problem is indeed the latest Google App update. Get rid of it...uninstall the update. Beginning yesterday I had the problem both on my S3 and Tablet 2 10. For months, I lost the sound on my cellphone when I did a Google search. The sound is back now as my phone has reverted back to the factory Google Search settings.