When my avatar began, I was a sort of peachy coloured cloud (Phoenix 1.6.1 viewer). I've found that you have a chance of your actual physical body rezzing if you input either a full avatar or features of the avatar. In my case, on my 3rd try, I gained the avatar's body when I changed the eyes. After that, the problem seems to be solved If it recurs, just do the same thing.
I hope that's helpful to you.
Darintara.