If you visit http://www.dragmath.bham.ac.uk/demo.html does that Dragmath look the same?
If that demo looks ok then your dragmath might miss some files or some settings (paths) might be wrong or some custom plugin in your IE might break code of Dragmath. If both look the same you could check your version of Java first.
Thanks a lot.I reinstall java 6 ,It work normal.But the function is simple.