Sidebar Block breaks

I've got the WPG2 plug-in installed in a number of different WordPress blogs. It works great in everyone except for this last install. When I add the Sidebar Block widget to the Sidebar it breaks the page layout, the HTML stops after this:

<li id="wpg2-sbar-block" class="widget wpg2_widget_sidebarblock_display">
<h2 class="widgettitle">Sidebar Block</h2>
<div>
<div class="wpg2sidebarblock-image">

I thought it might have been something in my theme code, so I tried a number of different themes. Then I took the theme and installed it on a site that the WPG2 plug-in was working on, no issues with the theme. The Sidebar Grid works fine.

I'm at my wits end trying to figure this one out and I'm wondering if it's something on the server side. I have no idea what else to check. This is also the same site that I'm having issues with trying to check the settings - clicking the Gallery2 Rewrites link will produce a blank page in the WordPress admin. If I deactivate the URL Rewrite in the Gallery2 admin the "blank page" issue goes away in the WP admin.

What else can I look for?

Thanks!
Leslie

WordPress version 2.9.1

Gallery version = 2.3.1 core 1.3.0.1
API = Core 7.54, Module 3.9, Theme 2.6, Embed 1.5
PHP version = 4.3.9 apache2handler
Webserver = Apache
Database = mysqlt 4.1.22, lock.system=flock
Toolkits = Gd
Acceleration = none, none
Operating system = Linux mosa.hostasaurus.com 2.6.9-89.0.11.ELsmp #1 SMP Tue Sep 15 07:08:59 EDT 2009 x86_64
Default theme = siriux
gettext = enabled
Locale = en_US
Browser = Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.5; en-US; rv:1.9.1.7) Gecko/20091221 Firefox/3.5.7
Rows in GalleryAccessMap table = 9
Rows in GalleryAccessSubscriberMap table = 10
Rows in GalleryUser table = 2
Rows in GalleryItem table = 10
Rows in GalleryAlbumItem table = 3
Rows in GalleryCacheMap table = 0