An extra directory (ruthless) is being written to the paths, firstly in your path to the gallery grid_fullsize:
ruthless.margoliswest.com/ruthless/Gallery/galleries/grid_fullsize/index.php?gallery=1&theme=light
if you remove it you at least get to the gallery:
index.php?gallery=1&theme=light
Similarly with the images once you reach that page, the image sources are including the extra (ruthless) directory in their paths. For example if you remove that from an image link on that page:
ruthless.margoliswest.com/ruthless/Gallery/images/1/buttons_gargoyle_lg_1289779137_782p.jpg
you get to the image file:
buttons_gargoyle_lg_1289779137_782p.jpg
[not that I know what to do about it]