Keith has an first gen Nexus 7 running Android Kit Kat. The launcher crashes after quitting certain mainstream apps. Leo says that he can try a different launcher. Leo uses the Nova Launcher. Google's Launcher and Apex are good choices too. Even Microsoft has a launcher.
Leo suggests Keith try Nova Launcher first. Leo has used it on his second gen Nexus 7 with no issues on Kit Kat 4.4.4. Keith can also do a factory reset to bring it back to the original configuration. He'll also want to be sure to turn off auto downloads of MMS messages. It can cause problems with on Android.