WinRM communicator "giving up"

[Martin]

Hi, 

Any one else had issues with the WinRM communicator just giving up?

I'm build ing 2012R2 machines using the vmware-iso builder on a 2012 R2 host. Sometimes packer just seems to stop getting feedback from the machines it's building. It will be executing a powershell script on the build and will stick on say removing a file. If I VNC onto the machines I can see that the script has actually completed but packer never seems to have gotten the message. 

Any one else seen anything like this?

Thanks in advance.