Yes. Only few visitors searching on my site, but many network searches and of course it is very good

I've just realized, that networking may be very dangerous
Let's suppose, that in the future, hundreds (or thousands) of Symbiostockers decide to put the same site into their network. For that site it may quickly "eat" all server resources, resembling DoS attack

Yes, (I 've edited my previous post above).
And those xml files are something that is not stored in your site, but generated and sent to  network site, as answer to network search.

I think that you should:
Go to your cpanel and try to change php settings (version, compatibility or something you can find there, to force php to accept deprecated parameter passing
or better
edit that symbiostock_image_processor.php file and in line 481 delete one &:
$size = GetImageSize( $dir . $file_name . '.jpg', &$info );
change to
$size = GetImageSize( $dir . $file_name . '.jpg', $info );
or even to
$size = getimagesize( $dir . $file_name . '.jpg', $info );

or ....
wait for Leo to do it

One issue discovered today: image processing should be case insensitive, or convert "JPG" to "jpg" in filenames at first
Now "JPG" file processing ends with some errors. I had to change extension to "jpg" in ftp folder.

Yesterday everything was ok, and today I tried test search with Fatal Error.

Below is part of your image with modified levels.
And I investigated, that it is resizing issue. Resized image, before watermark adding, already has stripes.

I didn't notice it before, because I used Imagick to resize images on my old server and there was no "banding". Now I moved my site to new host and  can use Symbiostock without modifications. It is visible only on white  surface.
My site may be sometimes down in next hours, so examples not mine:

http://stockimages.kerioak.com/image/old-wooden-clothes-airer/

http://photo.travelling-light.net/image/archive-file-boxes/

I will try to move my site to new server, so tomorrow it may be down. If someone is linking to me, please remove link, until it will be up again

Sometimes searching with active network is very long (over 30s), and in server log I found
"[Tue Apr 09 20:06:32 2013] [error] [client 108.59.8.80] WordPress database error MySQL server has gone away for query SELECT * FROM wp_posts WHERE ID = 8 LIMIT 1 made by require('wp-blog-header.php'), require_once('wp-includes/template-loader.php'), include('/themes/symbiostock/taxonomy-image-tags.php'), get_footer, locate_template, load_template, require_once('/themes/symbiostock/footer.php'), include_once('/themes/symbiostock/modal-login.php'), include_once('/themes/symbiostock/register_symbiostock.php'), get_permalink, get_post, WP_Post::get_instance
[Tue Apr 09 20:06:32 2013] [error] [client 108.59.8.80] WordPress database error MySQL server has gone away for query SELECT option_value FROM wp_options WHERE option_name = 'symbiostock_network_site_5' LIMIT 1 made by require('wp-blog-header.php'), require_once('wp-includes/template-loader.php'), include('/themes/symbiostock/taxonomy-image-tags.php'), network_manager->network_search_all_similar, get_option"

Not a bug maybe, I know that network communication needs improvement and some kind of reaction for timeouts etc, but maybe this info will be somehow helpful for Leo.

Go to your Symbiostock->Testing page and find in PHP Core table memory_limit entry. If it is lower than 256M,
then put in your php.ini line

memory_limit = 256M

and try to process files.

Look in this table also for other values, if they are the same as you put them in php.ini.

So.. let's start

When I click on "All images" in  admin area, I see error message
"Fatal error: Allowed memory size of 67108864 bytes exhausted (tried to allocate 44 bytes) in /home/ajt/ftp/stereoshutter/wp-includes/wp-db.php on line 1545"

I have 515 images now published.

I have disabled comments (I think), but they are only here and only after "process to publish".  After editing image everything is ok, these fields are not visible.