Safe Mode is a troubleshooting step. If the problem goes away in Safe Mode, then the problem lies with one of the apps you installed (i.e., not one of the preinstalled or system apps). The way this could happen after a Google Play Services update is if it causes a significant conflict with one of those apps. So if the problem goes away in Safe Mode, but comes back when you reboot normally, you need to go back into Safe Mode and start uninstalling apps one by one until the problem goes away.
Duplicate threads merged means I found another thread that you started, and merged the two, so that there aren't two identical threads active in the forums. Having two of the same thread can be confusing, since people in one thread may not know what those in the other thread have already suggested.