I recently installed the newsletter module (from http://svn.silverstripe.com/open/modules/newsletter/branches/0.4) to my Silverstripe 2.4.2 installation. The newsletter decorator uses dataobjects (named OneBlock) with DataObjectManager (from http://carlinowebdesign.svn.beanstalkapp.com/modules/trunk/dataobject_manager).
In worked fine on localhost, but after I moved it to the webhost Linux server the ajax that controls the popup for DOM stopped working. Instead the browser linked to this page .../admin/newsletter/NewsletterEditForm/field/OneBlocks/add and everything that should be shown in the popup window covered the whole browser.
At first alla DOMs were like this, but not it works with the DOMs on the regular page types.
I don't get any error messages and Silverstripe don't crash, but it's very complicated to create the dataobjects like this.