I am getting a strange Error message from my site saying that there is "Object Required".

Here is the section of code it is referring to (the section in bold is the area it said is the problem.):

nest=(!nest) ? '':'document.'+nest+'.'
this.el=bw.dom?document.getElementById(obj):bw.ie4?document.all[obj]:bw.ns4?eval(nest+'document.'+obj):0;
this.css=bw.dom?document.getElementById(obj).style:bw.ie4?document.all[obj].style:bw.ns4?eval(nest+'document.'+obj):0;
this.scrollHeight=bw.ns4?this.css.document.height:this.el.offsetHeight
this.clipHeight=bw.ns4?this.css.clip.height:this.el.offsetHeight
this.up=MoveAreaUp;this.down=MoveAreaDown;
this.MoveArea=MoveArea; this.x; this.y;
this.obj = obj + "Object"
eval(this.obj + "=this")
return this


Any clues?