seems when i try to upload an avatar that is within the restricted filesize/dimensions i get this message:

* The selected file /tmp/aksml1.jpg could not be uploaded, because the destination sites/default/files/pictures/picture-864.jpg is not properly configured.
* Failed to upload the picture image; the pictures directory doesn't exist or is not writable.

kinda strange. although with most forums you upload your avatar via an image hosting service such as tinypic, photobucket etc i haven't had any problems before.