I have a problem with changeing my Avatar.
When I upload a new one it shows every time the old one.
When I upload no file, it works and showing no Avatar in my profile but after I upload the new one, it shows the old one again.
That seems odd. Haven't experienced the problem before. How about re-downloading or trying to delete the old avatar that you used on your hard drive? And try resizing the new avatar that you want as well to 100x100 px. It might be that your image isn't resized to the required photo size that's why it's still showing your old one. Just a guess though, but still worth a shot.