Unfortunately Shopplugin.nl has experienced some massive database issues. It caused the website to respond extremely unexpected and the cause (and thus a solution) could not be found.
This means that Shopplugin.nl is shutting down.
But: this won't mean the end of the plugins. I'm working hard to getting the plugins updated so they'll work with Shopp 1.3+. They'll be added one-by-one on my Onexa website.
I'm really sorry for the inconvenience this may cause / have caused you, I'm doing the best I can to get the plugins updated and online again.