Nokia Lumia :: 800 Battery Consumption Increased - Screen Not Turning Off Itself

I noticed a couple of days ago that my phones battery consumption has increased considerably, from lasting just over a day I now only get to mid-evening before it needs recharging. I have also noticed that the screen isn't turning itself off (if I press the power button once the screen does go off but often the screen does comes back on) and the password requirement isn't kicking in.

I have tried setting the screen timeout to 30 seconds and the need for a password to one minute but the phone is ignoring my setting change. I haven't installed a new app nor changed an app settings recently either. I have done a hard reset (to factory settings) but this has made no difference (I also noted that the hard reset didn't roll back any updates either - Is this right?).