Just recently, I posted a thread inquiring about other junk cleaning apps because I had been having issues with Clean Master not working and constantly crashing on me (even sending crash messages when not in use). About 30 minutes ago, I was using Google Play to look at CCleaner. Clean Master also appeared in the search results and said that I was behind on updates.
I thought that it was a reasonable possibility that Clean Master was not working because I hadn't been updating it, so I went ahead and downloaded the update. Immediately after it was installed, the operating system was overloaded with hundreds of crash messages from every app on my tablet (including the Launcher, app store, apps that I hadn't used in months, and obscure data storages that meant nothing to normal usage) suddenly opening and crashing repeatedly. I was trying to clear all the messages but they continued appearing faster than I could get rid of them. I had to do a forced crash. I powered it back on and it continued, requiring a second forced crash. Third time, same thing. Fourth time, I used the button on the back to force it off. Fifth time on and it wouldn't even make it past the greeting screen. I took it to my dad and we messed with it for a bit, finally getting it to re-boot. I managed to get to the Clean Master app and uninstalled it immediately, and the crash messages instantly stopped.
I don't have any hell of an idea what happened there.