Just made a pav this morning, the vanilla snow one from the KA calender. No problem at all and I added the sugar at the start.

Is your bowl and whisk squeaky clean? A touch of greasiness is a killer for egg whites. Also how old are your eggs? Fresher is better.
All freshly washed and the first lot of eggs were five days old. The second were bought from the shop about three hours prior...
What is your sugar egg ratio and how long to you beat it for?
I want EXACT details. I'm going to nail this sucker. In a stubborn biarch XD