Single image element – external link is being opened with prettyphoto?

Hi, I’ve used the single image element to create some graphic links to internal and external pages.

I’ve set up the element as I should have:
On click action
Select action for click action.
OPEN CUSTOM LINK
(http://www.thecopperhorsecottages.co.uk/)

For some reason when you click on the images in the front end, the screen greys out as if there is an image is going to be viewed in prettyphoto or something like that

Can you offer any assistance?