Amazon Affiliate Links temporarly broken

I include some Amazon Aiffliate links as embedded html code in a part of my website project.
Now I get a strange behavior. When I load the website, some of these links go nowhere, i.e. the web server does not deliver the link URL stored in sparkle. Then when I reload the page url, some of those links work again, but others that worked before don’t.

You can test these here Link.

Reload the page and see which Amazon links are showing and which aren’t.
The affiliate url links itselfs created with a tool from the amazon website.
Anyone an idea?