Acces problem solved: As some of you may have noticed I couldn't acces the site for days. The problem was the Vodafone UMTS conscription! As soon as I was back on DSL I could connect.
Why Vodafone blocks acces is unkown to me. The vendor stated it may or may not be caused by a server blocking acces per cellphone numbers. Anyway, perhaps of use for other unlucky desperate ones..