<!-- Function to disable the enter key -->

function checkCR(evt) 
{

    var evt  = (evt) ? evt : ((event) ? event : null);

    var node = (evt.target) ? evt.target : ((evt.srcElement) ? evt.srcElement : null);

    if ((evt.keyCode == 13) && (node.type=="text")) {return false;}

}

  document.onkeypress = checkCR;



<!-- Another function to disable the enter key -->

function keyDown(DnEvents) 
{ 
if (document.all && !document.getElementById) {
     //IE 4 supports doucment.all but NOT document.getElementById
     k = window.event.keyCode;
	if (k == 13) {	// enter key pressed
		//eval('document.formSubscribers.' + nextfield + '.focus()');
		return false;
	}
} else if (document.layers) {
     //Netscape 4 only browser that supports document.layers
     k = DnEvents.which;
	if (k == 13) {	// enter key pressed
		//eval('document.formSubscribers.' + nextfield + '.focus()');
		return false;
	}
} else if (document.getElementById) {
     //Works for Netscape 6 and IE 5
	if (navigator.appName.toUpperCase().match(/MICROSOFT INTERNET EXPLORER/) != null)
	{
  		//document.write("You are using IE.");
		k = window.event.keyCode
		if (k == 13) {	// enter key pressed
		//eval('document.formSubscribers.' + nextfield + '.focus()');
		return false;
	}
	}else{
     k = DnEvents.which;
	if (k == 13) {	// enter key pressed
		//eval('document.formSubscribers.' + nextfield + '.focus()');
		alert("Function Disabled");
		return false;
     }
	
	}
} else {
     
}

}

document.onkeypress = keyDown;