I get the following error when I try to access the BlogHolder page in the CMS Admin page:

woe is me for trying the latest SVN build
But I needed the latest SVN build to clean up the formatting of the Blog pages ... otherwise the <br /> tags would make for a messy page.

(i.e. http://www.relevancefound.com/admin/?isDev=1, then click on "Blog")

ERROR:Error 256: Bad class to singleton() - NewsletterType
At l85 in /home1/relevanc/public_html/sapphire/core/Core.php
<ul>user_error(Bad class to singleton() - NewsletterType,256)
line 85 of Core.php

singleton(NewsletterType)
line 1569 of DataObject.php

DataObject::get(NewsletterType)
line 66 of BlogHolder.php

BlogHolder->getNewsletters()
line 54 of BlogHolder.php

BlogHolder->getCMSFields(CMSMain)
line 364 of CMSMain.php

CMSMain->getEditForm(5)
line 699 of LeftAndMain.php

LeftAndMain->EditForm()
line 239 of LeftAndMain.php

LeftAndMain->getitem(Array)
line 253 of Controller.php

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

Director::direct(admin/getitem)
line 144 of main.php

</ul>

Are you using the trunk version of the CMS as well? The newsletter module was part of the core but has recently been ripped out to a seperate module, so the blog module just needs to be updated to check for the newsletter module before trying to use it, this is probably the same with the Forum module which I think uses newsletters as well.

These modules will be updated soon hopefully