[horde] Horde App Setup Pages are blank: Fatal error: Call to undefined method domdocument::load()

[basem at netopiatech.com]

I have just installed the latest Horde Groupware 1.1 installed and  
everything works fine. I can send and receive emails no problem. But  
when I go to the admin setup pages for each app (/horde/admin/setup)  
and select any of the apps to configure (Address Book (turba),  
Calendar (kronolith), Dynamic Mail (dimp), etc), I get a blank white  
screen with these errors (I turned display_errors = On in my PHP5 ini  
file):

Warning: domdocument::domdocument() expects at least 1 parameter, 0
given in C:\webmail\horde\lib\Horde\DOM.php on line 119

Fatal error: Call to undefined method domdocument::load() in
C:\webmail\horde\lib\Horde\DOM.php on line 143

The /horde/test.php shows all required modules are fine. Does anybody  
know how I would fix this? I tried this in Firefox and Internet  
Explorer 7 with same problems. I checked all my permissions and they  
are fine. I'm guessing there's a problem loading up config.xml, but  
not really sure. Could this be a bug? I would appreciate any help or  
direction with this. Thanks in advance.

-Basem