I'm stuck in a loop when trying to checkout with version 4.4.1. Everything was working great, the friendly URLs were coming through. Navigating round the site has been good but when I go to Checkout I just get stuck in a loop at the login page. It looks like a redirect is forcing me back to login. I tried with and without the / on the rewrite rule, but have I missed something obvious?

Here are the log entries:

Code:
127.0.0.1 - - [05/Nov/2012:13:58:31 +1100] "GET /op-shop/index.php?main_page=login HTTP/1.1" 200 38435 "http://localhost/op-shop/index.php?main_page=login" "Mozilla/5.0 (Windows NT 5.1) AppleWebKit/537.4 (KHTML, like Gecko) Chrome/22.0.1229.94 Safari/537.4"
127.0.0.1 - - [05/Nov/2012:13:58:37 +1100] "POST /op-shop/index.php?main_page=login&action=process HTTP/1.1" 302 - "http://localhost/op-shop/index.php?main_page=login" "Mozilla/5.0 (Windows NT 5.1) AppleWebKit/537.4 (KHTML, like Gecko) Chrome/22.0.1229.94 Safari/537.4"
127.0.0.1 - - [05/Nov/2012:13:58:37 +1100] "GET /op-shop/index.php?main_page=checkout_shipping HTTP/1.1" 302 - "http://localhost/op-shop/index.php?main_page=login" "Mozilla/5.0 (Windows NT 5.1) AppleWebKit/537.4 (KHTML, like Gecko) Chrome/22.0.1229.94 Safari/537.4"
127.0.0.1 - - [05/Nov/2012:13:58:37 +1100] "GET /op-shop/index.php?main_page=login HTTP/1.1" 200 38419 "http://localhost/op-shop/index.php?main_page=login" "Mozilla/5.0 (Windows NT 5.1) AppleWebKit/537.4 (KHTML, like Gecko) Chrome/22.0.1229.94 Safari/537.4"