Logout button generating an error and not working

I am using Pulse with the latest Joomla!, 1.5.22 and using IE I am getting an error.

Webpage error details

User Agent: Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 6.1; WOW64; Trident/4.0; SLCC2; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729; Media Center PC 6.0; CPDTDF; .NET4.0C)
Timestamp: Mon, 15 Nov 2010 15:03:18 UTC


Message: 'null' is null or not an object
Line: 81
Char: 2
Code: 0
URI: http://www.budgie-print.co.uk/templates ... scripts.js

I have looked at the code and found this:
if(p.getStyle("display") != "block"){

If you put in a test for (p != null && ...
the code does not generate an error but the logout does not happen. I have tried using the default Joomla! template Milkyway and the logout button does work.

Site : www.budgie-print.co.uk
Login : test02
Pass : changethis

Note - this fault, being unable to logout, is happening in ALL of the browsers, Firefox, IE, Chrome.

Let me know if you need any more details.
David