The same thing happened to me when I was over at wall.fm and thought it was a path problem. I have since installed Oxwall on my own host and everything was fine until I updated my CSS file. At first I thought it was an error that I made in the CSS but before switching out the CSS I had saved the default one. When I replaced the default back still no icon images! This has got me baffled because the image files are in the directory and everything looks fine on the outside.

Thanks!