Thanks for all the responses!!!
I have disabled the face unlock app and it has now disappeared from my apps list. This solved the UI problem.
Unfortunately I now have an error message saying " Default Lock screeb disabled" but this only seems to be appearing when i open facebook!
Anyone else had this or know another fix??
i have HTC sensation XL i have the same problem what should i do?Same thing is happening to me...same time frame...same phone. My wallpaper is also going blank and then returning during this error. The only recent change I made was downloading Scout to replace TeleNav but I've removed it and I'm still getting the error.
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)