tool_base.css refers to an image file that does not exist, seeing lots of apache errors regarding this:
/for panels that "look" like forms but are read only ie. assignment preview - student view/
/see: preview an assignment - view the student view/
border: 1px solid #eee;
background: #fff url(images/ib.gif) top left repeat;
So either images/ib.gif needs to be added, or this needs to point to another file.