Resolving JavaScripts

I have two javascripts that I think are conflicting because one of them is not working. Can anyone tell me how to resolve?

MM_reloadPage(true);

function ClearField(FieldName){
var EmptyField = ""
eval('document.form1.' + FieldName + '.value = ""')

//-->

<!-- Begin
var isNN = (navigator.appName.indexOf("Netscape")!=-1);
function autoTab(input,len, e) {
var keyCode = (isNN) ? e.which : e.keyCode;
var filter = (isNN) ? [0,8,9] : [0,8,9,16,17,18,37,38,39,40,46];
if(input.value.length >= len && !containsElement(filter,keyCode)) {
input.value = input.value.slice(0, len);
input.form[(getIndex(input)+1) % input.form.length].focus();
}
function containsElement(arr, ele) {
var found = false, index = 0;
while(!found && index < arr.length)
if(arr[index] == ele)
found = true;
else
index++;
return found;
}
function getIndex(input) {
var index = -1, i = 0, found = false;
while (i < input.form.length && index == -1)
if (input.form[i] == input)index = i;
else i++;
return index;
}
return true;
}