This is an easy bug to replicate

1.Click to select a favor item

2.Click any favor item, the query "are you sure yes/no" will appear

3.Without closing it issue your demigod to enter a shop/citadel

This results in you unable to mouse click anything in the game UI. you are able to move your character but if you try to buy items/upgrades or select a skill from your skill tree(which you cant click to get into anyway, you can use hotkey though) it doesn't respond at all. You don't even have the mouse over effects.

It can be solved totally by pressing ESC but then the favor item you where queried about is picked for you, even if you never pressed yes and it took me a good 4 minutes or so to find out about ESC during the start of a game.