This isn't a huge problem, because I can work around it. We only allow our mods to have avatars, so this is a rare occurrence.
I became a user and tried to upload an avatar. I didn't get any error messages, but the avatar was not on the server when I checked. My assumption is (please correct me if I'm wrong) that uploaded avatars go to images/avatars and not images/avatars/default/. I verified that the directory is writable by the web server account. The image was resized (by me) to 71x80 to meet the requirements for avatars. I ended up scping the image to the server, placing it in the avatars directory and using the url to point to it.
I can't find where the path to avatars is defined in the Control Panel. Is it defined there?
Any hints on what (or where) to look for the answer? I looked in the webserver logs but didn't see anything regarding the upload. I also didn't see anything in the mysql or admin logs in Control Panel.