I have got exactly the same problem with both version 4 and 5. I am using a windows 7 (32bit x86) machine and do not have a firewall on. I have installed it on different Windows 7 machines and it has worked without a problem. The only difference in this machine and the ones it worked on is that there is Oracle VM VirtualBox installed on this machine which installs virtual NIC which could cause this problem.
I will uninstall the VM software and then try again and update this blog to let you know. Thanks