7D - Autofocus stopped working and blurry view through viewfinder

The autofocus of my year old 7D has just stopped working for no apparent reason. The view through the viewfinder is now blurry/hazy and the autofocus points overlay is no longer visible. Focussing is still possible manually and seems to work without problem through live view. I've reset all settings (not a dioptre issue) and that has had no effect. Has anyone experienced and hopefully resolved this?