epistable - 4:38 am on Sep 27, 2008 (gmt 0)

Do you have tagged links from your intranet that tag the campaign source as "intranet", or were you just using "intranet" to hide your site url on webmasterworld? If you are tagging the links, then try filtering on Campaign Source instead of on referal.

Also, wouldn't it be better to filter based on IP for your internal IP range? Surely not all internal visits are coming from the link on the intranet- many are probably direct.