Help! My site looks different when i log in.

Hi guys,

Yesterday i upgraded to version 3.1 from 3.0.5 and now for some unknown reason whenever i log in and view my site a random sand coloured border appears at the top of the page. This only appears when i view the site as a logged in user. If i view it as a general browser, it appears fine.

The site is ladiesgolftrousers.co.uk and if you load up the home page it should be displaying properly. However, this is a screenshot of the same page viewed as a logged in user. You can see the area in question right at the top of the page.

https://img217.imageshack.us/i/screenshot20110325at131.png/

Does anyone know why this is happening? I deactivated all my plug-ins and it still occurred.

Any help is much appreciated. Thanks