Base MAC address for eth0/NAT must be set error reported with 2 VMs

Logs

arnaud@mbp-arnaud:~/Code/eXo/puppet/vagrant/tqa (git:master)$ vagrant up
[as01] Box eXo-ubuntu-11.04-server-amd64_VBoxGuestAdditions-4.1.2 was not found. Fetching box from specified URL...
[as01] Downloading with Vagrant::Downloaders::HTTP...
[as01] Downloading box: https://storage.exoplatform.org/public/vagrant/ubuntu/11.04/eXo-ubuntu-11.04-server-amd64_VBGAddition-4.1.2.box
[as01] Extracting box...
[as01] Verifying box...
[as01] Cleaning up downloaded box...
[as01] Importing base box 'eXo-ubuntu-11.04-server-amd64_VBoxGuestAdditions-4.1.2'...
[as01] The guest additions on this VM do not match the install version of
VirtualBox! This may cause things such as forwarded ports, shared
folders, and more to not work properly. If any of those things fail on
this machine, please update the guest additions and repackage the
box.

Guest Additions Version: 4.1.2
VirtualBox Version: 4.1.6
[as01] Preparing host only network...
[as01] Creating new host only network for environment...
[as01] Matching MAC address for NAT networking...
[as01] Clearing any previously set forwarded ports...
[as01] Forwarding ports...
[as01] -- http: 80 => 10080 (adapter 1)
[as01] -- ssh: 22 => 2222 (adapter 1)
[as01] Creating shared folders metadata...
[as01] Running any VM customizations...
[as01] Booting VM...
[as01] Waiting for VM to boot. This can take a few minutes.
[as01] VM booted and ready for use!
[as01] Enabling host only network...
[as01] Setting host name...
[as01] Mounting shared folders...
[as01] -- v-root: /vagrant
[as01] -- v-files: /tmp/vagrant-puppet/files
[as01] -- v-templates: /tmp/vagrant-puppet/templates
[as01] -- manifests: /tmp/vagrant-puppet/manifests
[as01] -- v-pp-m0: /tmp/vagrant-puppet/modules-0
[as01] Running provisioner: Vagrant::Provisioners::Puppet...
[as01] Running Puppet with nodes/tqa-as01.exoplatform.org.pp...
[as01] stdin: is not a tty
[as01] notice: /Stage[main]/Htop::Install/Package[htop]/ensure: ensure changed 'purged' to 'present'
[as01] notice: /Stage[main]/Puppet/File[/etc/apt/sources.list.d/puppet.list]/ensure: defined content as '{md5}1338a0bf6bd88714577c754c973e36dd'
[as01] notice: /Stage[main]/Puppet/Package[rubygems1.8]/ensure: ensure changed 'purged' to 'latest'
[as01] notice: /Stage[main]/Puppet/Package[puppet]/ensure: ensure changed 'purged' to 'latest'
[as01] notice: /Stage[main]/Ntp::Config/File[/etc/ntp.conf]/content: content changed '{md5}32280703a4ba7aa1148c48895097ed07' to '{md5}79e6efe56ad760c4fb0a1eb6d0ed7bed'
[as01] notice: /Stage[main]/Ntp::Service/Service[ntp]: Triggered 'refresh' from 1 events
[as01] 
[as01] notice: Finished catalog run in 80.66 seconds
There was a problem with the configuration of Vagrant. The error message(s)
are printed below:

vm:
* Base MAC address for eth0/NAT must be set. Contact box maintainer for more information.