potrebbe essere un problema di browser?

mi hanno consigliato di sostituire la funzione browsercheck con questa:
ma non va lo stesso


function
lib_bwcheck(){
this.ver=navigator.appVersion; this.agent=navigator.
userAgent
this.dom=document.getElementById?1:0
this.ie5=(this.ver.
indexOf("MSIE 5")>-1 && this.dom)?1:0;
this.ie6=(this.ver.indexOf
("MSIE 6")>-1 && this.dom)?1:0;
this.ie7=(this.ver.indexOf("MSIE 7")>-
1 && this.dom)?1:0;
this.ie4=(document.all && !this.dom)?1:0;
this.
ie=this.ie4||this.ie5||this.ie6 || this.ie7
this.mac=this.agent.indexOf
("Mac")>-1
this.opera5=this.agent.indexOf("Opera 5")>-1
this.ns6(this.dom && parseInt(this.ver) >= 5) ?1:0;
this.ns7=(this.dom &&
parseInt(this.ver) >= 5) ?1:0;
this.ns4=(document.layers && !this.dom)?
1:0;
this.bw=(this.ie7 || this.ie6 || this.ie5 || this.ie4 || this.ns4
|| this.ns6 || this.opera5 || this.dom)
return this
}