url rewrite error (ERROR_STORAGE_FAILURE)

hi there,
i was wondering if anyone has experienced this error message before and/or knows some hints to fix the issue.
i'm running Gallery 2.1 embedded in Drupal 4.7 and have been fiddling around with the 'url rewrite' issues that came along with it. after finding out there seems to be an issue with the drupal module 'gallery.module' in terms of applying the rewrite rules to the .htaccess files (and fixing this via coding the .htaccess files directly) there is one last issue which i can't figure out where it comes from.
below is the error out put generated opening a picture in the drupal embeded environment in the gallery. (note that the page displays the right picture but also prints the error message)

you can see the error live at:
http://www.beyondtrails.com/gallery/WesternCanada/Winter/DogSleddingSkyH...

error output on single image gallery page (photo.tpl):

Error (ERROR_STORAGE_FAILURE)

    * in modules/core/classes/GalleryStorage/GalleryStorageExtras.class at line 988 (gallerycoreapi::error)
    * in modules/core/classes/GalleryStorage.class at line 501 (gallerystorageextras::addmapentry)
    * in modules/core/classes/GalleryCoreApi.class at line 2923 (mysqlstorage::addmapentry)
    * in modules/core/classes/GalleryDataCache.class at line 739 (gallerycoreapi::addmapentry)
    * in modules/core/classes/GalleryTheme.class at line 1727 (gallerydatacache::putpagedata)
    * in themes/floatrix/theme.inc at line 111 (floatrixtheme::loadcommontemplatedata)
    * in modules/core/classes/GalleryTheme.class at line 922 (floatrixtheme::showphotopage)
    * in modules/core/classes/GalleryView.class at line 325 (floatrixtheme::loadtemplate)
    * in main.php at line 386 (showitemview::doloadtemplate)
    * in main.php at line 87
    * in modules/core/classes/GalleryEmbed.class at line 192
    * in /home/client/public_html/beyondtrails/modules/gallery/gallery_block.inc at line 86 (galleryembed::handlerequest)
    * in /home/client/public_html/beyondtrails/modules/gallery/gallery.module at line 186
    * in ??? at line 0
    * in /home/client/public_html/beyondtrails/includes/module.inc at line 185
    * in /home/client/public_html/beyondtrails/modules/block.module at line 638
    * in ??? at line 0
    * in /home/client/public_html/beyondtrails/includes/module.inc at line 185
    * in /home/client/public_html/beyondtrails/includes/theme.inc at line 935
    * in ??? at line 0
    * in /home/client/public_html/beyondtrails/includes/theme.inc at line 166
    * in /home/client/public_html/beyondtrails/themes/engines/phptemplate/phptemplate.engine at line 160
    * in ??? at line 0
    * in /home/client/public_html/beyondtrails/includes/theme.inc at line 166
    * in /home/client/public_html/beyondtrails/index.php at line 29

System Information
Gallery version 	2.1.1
PHP version 	4.4.1 cgi
Webserver 	Apache/1.3.34 (Unix) mod_fastcgi/2.4.2 mod_auth_passthrough/1.8 mod_log_bytes/1.2 mod_bwlimited/1.4 FrontPage/5.0.2.2635 mod_ssl/2.8.25 OpenSSL/0.9.7a PHP-CGI/0.1b
Database 	mysqlt 4.1.14-standard-log
Toolkits 	SquareThumb, ImageMagick, NetPBM, Gd
Operating system 	Linux host.com 2.6.9-34.ELsmp #1 SMP Thu Mar 9 06:23:23 GMT 2006 x86_64
Browser 	Mozilla/5.0 (Macintosh; U; PPC Mac OS X Mach-O; en-US; rv:1.8.0.3) Gecko/20060426 Firefox/1.5.0.3

thanks for any help or hints,
felix

btw, this error appears irregular. ;)