My Evo Design 4G has been quitting for the last 2 days as well. I don't even know what "face lock" is so I doubt that's my problem. I don't want to do a factory reset & lose everything on my phone either. In general it's the slowest phone ever. It takes forever to open up any app. I don't even have 1/4 of the memory full so I know it's not that. I'm really starting to hate this phone. It never connects anywhere when other people can. My contract isn't up until Feb though.
I found an app ( Settings / Apps / All ) called Face Lock. I didn't know what it was so did a search. I disabled it. I did not reboot just disabled it. No error messages since. That was 3 hours ago. They were happening even when it was just laying there. I just took a bunch of pictures and then put them in photogrid to upload to Instagram and no error message and the battery is full green. (crossing my fingers)