Alistair is invisible

Alistair is invisible.I can't click on him. The only way I know he is there is when he talks & I can read it. The game was going well all day & now this. I downloaded mods last night,but doubt they have anything to do with him becoming invisible,right after the Landsmeet. I didn't get the little speech about the engagement,either. The door opened & he went poof! Haven't seen him since,and he's no longer in my Party. Please help!

My computer upgraded itself to Windows 8.1 early this morn. Would that have something to do with this?