Its because one of my email accounts is failing to sync. I had to get on my computer and unlink Facebook from my windows phone in order to make my windows account sync. After this my phone was cool and went back to normal. Today my Facebook wouldn't sync dropping my battery 30 percent in 3 hours on standby but I just turned my phone off and on again. If your having problems check that your phone is properly syncing. Just another thing to troubleshoot.