While some of the error message I don't understand the language, I can pick out some important bits. It appears that you're attempting to add the nodes through Mozilla, have you tried using Internet Explorer to do the same tasks?
Are you getting this error when you attempt to add a single node or does it happen when using the Network Discovery tool?
Also, I found a few thwack posts with the error 'Object reference not set to an instance of an object', here is a post with possibly a direction to check:
Hope this helps!
Hi, thanks for answering.
I have tried both IE og Firefox, and on lots of different computers, same error.
The link you posted didn't fit either.
Think I'll send it to support.