registered users seeing 404 on thumbnails, and TMP_SESSION_ID

Hi,

I getting intermittent broken thumbnails for registered users, when the images don't load I'm seeing, TMP_SESSION_ID returned in the header.

I'm running latest versions of gallery2, wordpress and wp2g.

thanks!

System info:
Last Run Details:

Gallery URL = http://###/gallery/main.php
Gallery version = 2.3 core 1.3.0
API = Core 7.54, Module 3.9, Theme 2.6, Embed 1.5
PHP version = 5.2.5 cgi-fcgi
Webserver = Apache
Database = mysqlt 5.0.67-log, lock.system=flock
Toolkits = Exif, LinkItemToolkit, SquareThumb, Thumbnail, ImageMagick, Gd
Acceleration = none/0, full/86400
Operating system = Linux linhost112.mesa1.secureserver.net 2.4.21-53.ELsmp #1 SMP Wed Nov 14 03:54:12 EST 2007 i686
Default theme = tile
gettext = enabled
Locale = en_US
Browser = Mozilla/5.0 (Windows; U; Windows NT 6.0; en-US) AppleWebKit/525.19 (KHTML, like Gecko) Chrome/1.0.154.36 Safari/525.19
Rows in GalleryAccessMap table = 6
Rows in GalleryAccessSubscriberMap table = 839
Rows in GalleryUser table = 15
Rows in GalleryItem table = 837
Rows in GalleryAlbumItem table = 70
Rows in GalleryCacheMap table = 387