I am using this piece of code and Windows debug comes up with an error for:
form = document.getElementById('form');

The code seems to work in all browsers apart from IE?

<script language="javascript">
$(document).ready(function() {
	
	var loading;
	var results;
	
	form = document.getElementById('form');
	loading = document.getElementById('loading');
	results = document.getElementById('results');
	
	$('#Submit').click( function() {
		
		if($('#Search').val() == "")
		{alert('please enter a domain');return false;}
		
		results.style.display = 'none';
		$('#results').html('');
		loading.style.display = 'inline';
		
		$.post('process.php?domain=' + escape($('#Search').val()),{
		}, function(response){
			
			results.style.display = 'block';
			$('#results').html(unescape(response));	
			loading.style.display = 'none';
		});
		
		return false;
	});
	
});
</script>

try to use other then "form" as id for your form....
FORM is a reserved word for IE.

Here is a simplified version of the page

As I said, it seems to work in all but Internet Explorer although I'm wondering if there may be a CSS problem as well that is causing it...

As alexsts said, the problem is the line form = document.getElementById('form');"form" is a reserved word - change it to my_form or whatever.

Sorry, I should have read post 2 better!
I was changing the <form> name...

Changed the document.getElementById and it works fine now.

Cheers!