I just did a fresh installation of latest version of SS. I was setting up a site and couldn't get Newsletter form getting work.
When I view the page I see this error..

FATAL ERROR: Invalid argument supplied for foreach()
At line 266 in /Applications/xampp/xamppfiles/htdocs/silverstripe/cms/code/Newsletter/SubscribeForm.php

SubscribeForm_Controller->Form()

call_user_func_array(Array,Array)
line 404 of ViewableData.php

ViewableData->XML_val(Form,,1)
line 203 of .cache.Applications.xampp.xamppfiles.htdocs.silverstripe.themes.blackcandy.templates.Layout.Page.ss

include(/Applications/xampp/xamppfiles/htdocs/silverstripe/silverstripe-cache/.cache.Applications.xampp.xamppfiles.htdocs.silverstripe.themes.blackcandy.templates.Layout.Page.ss)
line 197 of SSViewer.php

SSViewer->process(SubscribeForm_Controller)
line 189 of SSViewer.php

SSViewer->process(SubscribeForm_Controller)
line 296 of Controller.php

Controller->defaultAction(index,Array)
line 267 of Controller.php

Controller->run(Array)
line 22 of ModelAsController.php

ModelAsController->run(Array)
line 104 of Director.php

Director::direct(/newsletter/)
line 158 of main.php
Context
Debug (Debug::showError() in line 180 of Debug.php)

    * form =
      Form
          o EmailFieldEmailField (EditableEmailField17: Email address : ) =
          o TextFieldTextField (EditableTextField18: Your name : ) =
          o TextareaFieldTextareaField (EditableTextField20: Address : ) =
          o TextFieldTextField (EditableTextField21: Job title : ) =
          o TextFieldTextField (EditableTextField22: Organisation : ) =
          o HiddenFieldHiddenField (Referrer: : ) = http://localhost/silverstripe/
      Validator
          o EditableEmailField17
          o EditableTextField18
    * newsletterList =

    * newsletters = 

Is that the 2.3rc latest version of Silverstripe or the latest stable 2.2.3?. You might like to test using the latest 2.3rc3 of SilverStripe and the latest daily build from the newsletter download page and see if that works.

I had the same problem with 2.3.1 version, trying to add one "Subscribe Form".
I think maybe one problem with "there's no newsletter yet" and I've added new newsletter and the page was opened right.

I had no time now to debug in deep and I think this comment maybe help future release.

Thanks