Actually that was with VAGRANT_LOG=DEBUG.
Below is the full output as of when ssh is invoked, but it doesn't seem to log any ssh errors. I also watched the auth logs on the windows guest and I never saw a vagrant user attempt to login.
INFO ssh: Execute: shutdown /s /t 1 /c "Vagrant Halt" /f /d p:4:1 (sudo=false)
DEBUG ssh: Exit status: 1
ERROR warden: Error occurred: The following SSH command responded with a non-zero exit status.
Vagrant assumes that this means the command failed!
shutdown /s /t 1 /c "Vagrant Halt" /f /d p:4:1
ERROR warden: Error occurred: The following SSH command responded with a non-zero exit status.
Vagrant assumes that this means the command failed!
shutdown /s /t 1 /c "Vagrant Halt" /f /d p:4:1
ERROR warden: Error occurred: The following SSH command responded with a non-zero exit status.
Vagrant assumes that this means the command failed!
shutdown /s /t 1 /c "Vagrant Halt" /f /d p:4:1
ERROR warden: Error occurred: The following SSH command responded with a non-zero exit status.
Vagrant assumes that this means the command failed!
shutdown /s /t 1 /c "Vagrant Halt" /f /d p:4:1
ERROR warden: Error occurred: The following SSH command responded with a non-zero exit status.
Vagrant assumes that this means the command failed!
shutdown /s /t 1 /c "Vagrant Halt" /f /d p:4:1
ERROR vagrant: C:/vagrant/vagrant/embedded/lib/ruby/gems/1.9.1/gems/vagrant-1.0.3/lib/vagrant/communication/ssh.rb:62:in `execute'
C:/vagrant/vagrant/embedded/lib/ruby/gems/1.9.1/gems/vagrant-1.0.3/lib/vagrant/guest/windows.rb:41:in `halt'
C:/vagrant/vagrant/embedded/lib/ruby/gems/1.9.1/gems/vagrant-1.0.3/lib/vagrant/action/vm/halt.rb:14:in `call'
C:/vagrant/vagrant/embedded/lib/ruby/gems/1.9.1/gems/vagrant-1.0.3/lib/vagrant/action/warden.rb:33:in `call'
C:/vagrant/vagrant/embedded/lib/ruby/gems/1.9.1/gems/vagrant-1.0.3/lib/vagrant/action/vm/discard_state.rb:17:in `call'
C:/vagrant/vagrant/embedded/lib/ruby/gems/1.9.1/gems/vagrant-1.0.3/lib/vagrant/action/warden.rb:33:in `call'
C:/vagrant/vagrant/embedded/lib/ruby/gems/1.9.1/gems/vagrant-1.0.3/lib/vagrant/action/vm/check_accessible.rb:18:in `call'
C:/vagrant/vagrant/embedded/lib/ruby/gems/1.9.1/gems/vagrant-1.0.3/lib/vagrant/action/warden.rb:33:in `call'
C:/vagrant/vagrant/embedded/lib/ruby/gems/1.9.1/gems/vagrant-1.0.3/lib/vagrant/action/general/validate.rb:13:in `call'
C:/vagrant/vagrant/embedded/lib/ruby/gems/1.9.1/gems/vagrant-1.0.3/lib/vagrant/action/warden.rb:33:in `call'
C:/vagrant/vagrant/embedded/lib/ruby/gems/1.9.1/gems/vagrant-1.0.3/lib/vagrant/action/general/check_virtualbox.rb:23:in `call'
C:/vagrant/vagrant/embedded/lib/ruby/gems/1.9.1/gems/vagrant-1.0.3/lib/vagrant/action/warden.rb:33:in `call'
C:/vagrant/vagrant/embedded/lib/ruby/gems/1.9.1/gems/vagrant-1.0.3/lib/vagrant/action/builder.rb:92:in `call'
C:/vagrant/vagrant/embedded/lib/ruby/gems/1.9.1/gems/vagrant-1.0.3/lib/vagrant/action/runner.rb:49:in `block in run'
C:/vagrant/vagrant/embedded/lib/ruby/gems/1.9.1/gems/vagrant-1.0.3/lib/vagrant/util/busy.rb:19:in `busy'
C:/vagrant/vagrant/embedded/lib/ruby/gems/1.9.1/gems/vagrant-1.0.3/lib/vagrant/action/runner.rb:49:in `run'
C:/vagrant/vagrant/embedded/lib/ruby/gems/1.9.1/gems/vagrant-1.0.3/lib/vagrant/vm.rb:192:in `run_action'
C:/vagrant/vagrant/embedded/lib/ruby/gems/1.9.1/gems/vagrant-1.0.3/lib/vagrant/vm.rb:156:in `halt'
C:/vagrant/vagrant/embedded/lib/ruby/gems/1.9.1/gems/vagrant-1.0.3/lib/vagrant/command/halt.rb:27:in `block in execute'
C:/vagrant/vagrant/embedded/lib/ruby/gems/1.9.1/gems/vagrant-1.0.3/lib/vagrant/command/base.rb:116:in `block in with_target_vms'
C:/vagrant/vagrant/embedded/lib/ruby/gems/1.9.1/gems/vagrant-1.0.3/lib/vagrant/command/base.rb:111:in `each'
C:/vagrant/vagrant/embedded/lib/ruby/gems/1.9.1/gems/vagrant-1.0.3/lib/vagrant/command/base.rb:111:in `with_target_vms'
C:/vagrant/vagrant/embedded/lib/ruby/gems/1.9.1/gems/vagrant-1.0.3/lib/vagrant/command/halt.rb:24:in `execute'
C:/vagrant/vagrant/embedded/lib/ruby/gems/1.9.1/gems/vagrant-1.0.3/lib/vagrant/cli.rb:42:in `execute'
C:/vagrant/vagrant/embedded/lib/ruby/gems/1.9.1/gems/vagrant-1.0.3/lib/vagrant/environment.rb:167:in `cli'
C:/vagrant/vagrant/embedded/lib/ruby/gems/1.9.1/gems/vagrant-1.0.3/bin/vagrant:43:in `<top (required)>'
C:/vagrant/vagrant/bin//../embedded/bin/vagrant:19:in `load'
C:/vagrant/vagrant/bin//../embedded/bin/vagrant:19:in `<main>'
INFO interface: error: The following SSH command responded with a non-zero exit status.