[Mediawiki-l] Internal error after upgrading from 1.9.1 to 1.12.0

[Shannon Adams]

I just upgraded from MediaWiki 1.9.1 to 1.12.0.

PHP      5.0.4 (apache2handler)
MySQL     4.1.20-log

Everything appears to work fine, except for when trying to edit using the [edit] option located on the far-right of any page.  I can use edit located on any tab fine, but if I click [edit] on far-right of any page, I get:

Invalid h node passed to PPNode_DOM::splitHeading

Backtrace:

#0 /var/www/html/intranet/wiki-it/includes/Preprocessor_DOM.php(1348): PPNode_DOM::splitHeading()
#1 /var/www/html/intranet/wiki-it/includes/Parser.php(4605): PPNode_DOM->splitHeading()
#2 /var/www/html/intranet/wiki-it/includes/Parser.php(4675): Parser->extractSections('{| width="100%"...', '2', 'get', false)
#3 /var/www/html/intranet/wiki-it/includes/EditPage.php(193): Parser->getSection('{| width="100%"...', '2', false)
#4 /var/www/html/intranet/wiki-it/includes/EditPage.php(982): EditPage->getContent(false)
#5 /var/www/html/intranet/wiki-it/includes/EditPage.php(473): EditPage->initialiseForm()
#6 /var/www/html/intranet/wiki-it/includes/EditPage.php(323): EditPage->edit()
#7 /var/www/html/intranet/wiki-it/includes/Wiki.php(444): EditPage->submit()
#8 /var/www/html/intranet/wiki-it/includes/Wiki.php(48): MediaWiki->performAction(Object(OutputPage), Object(Article), Object(Title), Object(User), Object(WebRequest))
#9 /var/www/html/intranet/wiki-it/index.php(90): MediaWiki->initialize(Object(Title), Object(OutputPage), Object(User), Object(WebRequest))
#10 {main} 

Any ideas?  This did not happen on 1.9.1.

Thanks,
Shannon