I have the same problem. I get extremely anxious whenever I am in charge of planning a social event but if one of my friends plans something I always have a great time when I attend.
As a slight variation on the same theme - just the anticipation of a social event can make me quite anxious and edgy regardless of whether I've been part of the planning.
The thing that fixes it for me is going to events with a clear group activity other than "generic socializing".
