There is no option to change the URL that the blog profile pictures are using. At the moment the pictures are loading at the root site, not with a /blog extension.
For example, the images are trying to load at:
http://www.maelstrome-designs.co.uk/wp-content/profile-pics/3.jpg when it should be loading at:
I have changed the settings in the main dashboard to reflect this, and it's still happening.