I have had this problem for a couple of days on my first-generation Motorola Moto G. Normally a restart would fix it. However now I am faced with the following error message when trying to unlock the phone after a restart:
Unfortunately the process com.android.systemui has stopped.
The phone has reset the background to the default home screen which disappears when I unlock, going to a black screen. However, it still shows my apps and widgets. Then a second or so later goes back to the unlock screen.
I have tried clearing the cache partition multiple times which has not worked. Ss there any way I can fix this problem without a factory reset, or taking my phone to a phone shop?
Some additional information:
I have been using ART on my phone for the past couple of months, but the problem has only occurred recently
On boot-up I get the following message:
Updating Android. Optimizing app 1 of 1.