Javascript der ikke vireker i FF men i IE

Denne kode: (Er desværre meget lang, beklager)

var debugActive = true;
function debug( txt ) {
    if ( debugActive ) debugActive=confirm( txt );
}; //end debug( string )


function verifyCompatibleBrowser(){
    this.ver=navigator.appVersion
    this.dom=document.getElementById?1:0
    this.ie5=(this.ver.indexOf("MSIE 5")>-1 && this.dom)?1:0;
    this.ie4=(document.all && !this.dom)?1:0;
    this.ns5=(this.dom && parseInt(this.ver) >= 5) ?1:0;
    this.ns4=(document.layers && !this.dom)?1:0;
    this.bw=(this.ie5 || this.ie4 || this.ns4 || this.ns5)
    return this
}
bw=new verifyCompatibleBrowser()


var speed=50

var loop, timer

function ConstructObject(obj,nest){
    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.scrollWidth=bw.ns4
                    ? this.css.document.width
                    : this.el.offsetWidth;
    this.clipWidth=bw.ns4
                  ? this.css.clip.width
                  : this.el.offsetWidth;
    this.leftx= MoveAreaLeft;
    this.rightx=MoveAreaRight;
    this.MoveArea=MoveArea;
    this.x;
    this.y;
    this.obj = obj + "Object"
    eval(this.obj + "=this")
    return this
}
function MoveArea(x,y){
    this.x=x; this.y=y;
    this.css.left=this.x;
    this.css.top=this.y;
}

function MoveAreaRight(move){
//  debug ( "MoveAreaRight("+move+") kaldt. this.x = " +this.x );
//  debug ( "bredde "+ 320 +" -" +this.scrollWidth );
//    if(this.x>objContainer.clipWidth-this.scrollWidth){
    if(this.x>674-this.scrollWidth){
    this.MoveArea(this.x-move,0)
    if(loop) setTimeout(this.obj+".rightx("+move+")",speed)
    }
}
function MoveAreaLeft(move){
//  debug ( "MoveAreaLeft("+move+") kaldt. this.x = " +this.x );
    if(0>this.x){
    this.MoveArea(this.x-move,0)
    if(loop) setTimeout(this.obj+".leftx("+move+")",speed)
    }
}

function PerformScroll(speed){
//  debug ( "PerformScroll("+speed+") kaldt" );
    if(initialised){
        loop=true;
        if(speed>0) objScroller.rightx(speed)
        else objScroller.leftx(speed)
    }
}

function CeaseScroll(){
    loop=false
    if(timer) clearTimeout(timer)
}
var initialised;
function InitialiseScrollableArea(){
    objContainer=new ConstructObject('divContainer');
    objScroller=new ConstructObject('divContent','divContainer');
    objScroller.MoveArea(0,0);
    objContainer.css.visibility='visible';
    initialised=true;
}
// end absolutely positioned scrollable area object scripts


Virker i IE men ikke i FireFox.
Hvilke ting skal man være opmærksom på for at de virker begge steder. Det virker i øvrigt heller ikke på MAC.