My guess is that with the “href” parameter you’re supposed to indicate an element on the page that you want to put in the box (like you did with ‘.inline’). “#” doesn’t point to anything on the page, so therefore it causes an error.
By the way, when I click the tabs, the footer jumps up into view during the transition. It’s quite annoying, so you need to fix that!
As for your jumping footer, it’s related to the height of your content. To avoid the jumping, you have to ensure the height does not become 0 during the transition. This will probably mean setting the height of the wrapper to the height of the new content.
Instead of sliding Content up and down, slide #photos, #technical_details and #details up and down. You could also set some opacity transitions at the same time, to give the effect of one dissolving into the other.
By the way, your use of the H1 element is wrong. You should not be using more than one H1 element on your page. The way you’re using them, they should be H2 or H3s.
Also, you might want to consider merging your JS and CSS files into one to avoid making so many HTTP requests. There is an automatic method for this described at http://rakaz.nl