Not sure on the whole avatar thing, and what glitches keep messing them up. I see avatars come and go all the time on this forum, with large numbers of the generic "Tin-Tin" profile, including my own.
Every avatar pic I have tried to attach only lasts a couple of days at most, then returns to generic. I have shrunk stuff to 100 x 100 pixels, used random photos, personal and non-personal photos, but nothing sticks. I'm using Google Chrome btw.