curl: (56) Recv failure node.js on virtualbox

I have installed node.js on a virtual-box machine. I started the webserver example from nodejs.org, curl-ed from the virtual machine and got "hello world".
then i forwarded port 8000 on the host to the example-port on the guest. when i curl the forwarded port on the guest i get:

curl: (56) Recv failure: Connection reset by peer


What is the problem?