It thought it was the Shopp plug-in that did not do what it was suppost to do but it seems to be atahualpa which messes up. I make products in the Shopp plug in and in the overview I see the products, when I hoover I see the respective URL's. But when I click on the second product, I will get to see the first and when I click on the third product I see the first etc. The URL's are what they are suppost to be but it keeps showing me product one in the wrong place, in the wrong url.

So after complaining at the Shopp people I found out that with standard theme activated the problem doesn't excist...

What can be the matter here?

what version of atahualpa and WP?
What is the url?

Atahualpa 3.4.2 and then I tried 3.4.4. and running wp 2.8.4, the latest. the url http://www.aheadoftheherd.eu/wordpress/shop/
hoover over the product images. they point to the correct url's but keep showing the same image.

Please swap back to the default theme and let me know when you have and I'll take a look

done, it's now in default theme

Well you are right, there seems to be an interaction. Problem is, I don't have that plugin to look at it and it costs money to purchase so I can't look at it.