"Process system not responding" in Android - freeze plus reboot loop

After changing the SIM card or playing with WiFi settings in your Android device (stock or otherwise), you may see "Process system not responding" with a forced reboot.

This is what worked for me. Take your pick from the easiest to the hardest one: 

• Remove the battery. Let the power drain for 10 seconds and reinsert it. (Yes, only that.)
• Clear Dalvik Cache in the Recovery Mode.
• Change the boot animation to a shorter one. Try this one.
• Remove the Google Backup service. See here.