I have installed simple image gallery plugin .. on time it works fine but after an hour moving cms to the root now getting an error.

Error is : JW_SIG_PRG
bucsoccer.com/
the plugin is not loaded the plugin is enabled from backend.

Where do you get this error?

I get the same error on first page
www.sportnodrustvozadvor.si/testjom/
This is my test joomla and i have {gallery}galerija{/gallery} as you can see it below.
On my ftp i have files in images/galerija
Plugin is loaded on first page and it never shows images.
In administration in plugin i selected folder images instead of images/stories.
I have Joomla 1.6.0 and latest simple gallery 2.1.
Any idea? :)

I get the same error

I am getting this error as well.  It is at the top of the article that I display in.  This is a copy of my error log that comes when I reload the page.

localhost ~ # php -v
PHP 5.3.6 (cli) (built: May 10 2011 16:47:30)
Copyright (c) 1997-2011 The PHP Group
Zend Engine v2.3.0, Copyright (c) 1998-2011 Zend Technologies

GD Support => enabled
GD Version => bundled (2.0.34 compatible)
GIF Read Support => enabled
GIF Create Support => enabled
JPEG Support => enabled
libJPEG Version => 8
PNG Support => enabled
libPNG Version => 1.4.2
WBMP Support => enabled
XBM Support => enabled

Directive => Local Value => Master Value
gd.jpeg_ignore_warning => 0 => 0

localhost ~ # ldd /usr/local/bin/php
libpng14.so.14 => /usr/local/lib/libpng14.so.14 (0x008f8000)
libjpeg.so.62 => /usr/lib/libjpeg.so.62 (0x00dc8000)

[Fri May 13 09:46:40 2011] [error] [client 67.138.129.34] PHP Warning:  imagecreatefromjpeg() [<a href='function.imagecreatefromjpeg'>function.imagecreatefromjpeg</a>]: gd-jpeg: JPEG library reports unrecoverable error:  in /var/www/vhosts/demo.binmarketinggroup.com/www/plugins/content/jw_simpleImageGallery/jw_simpleImageGallery/includes/helper.php on line 105
[Fri May 13 09:46:40 2011] [error] [client 67.138.129.34] PHP Warning:  imagecreatefromjpeg() [<a href='function.imagecreatefromjpeg'>function.imagecreatefromjpeg</a>]: '/var/www/vhosts/demo.binmarketinggroup.com/www/images/myfolder/top-banner.jpg' is not a valid JPEG file in /var/www/vhosts/demo.binmarketinggroup.com/www/plugins/content/jw_simpleImageGallery/jw_simpleImageGallery/includes/helper.php on line 105

I have png and gif working just fine.  I can use jpg as well, this error is part of a problem with the file that I am using.  The plugin doesn't check the files mime type and when it is passed to the function the error log is hit with that message.  You should check file type and then pass and exception correctly.  You have a exception in helper.php line 95 but you don't have the error passing correctly

$source = getimagesize($found);
    $type = array('image/jpg', 'image/jpeg', 'image/png', 'image/gif');

    if(in_array($found, $allowedMimes))
      $source = @ imagecreatefromgif($original); etc
    else
      $error = JText::_('Not a mime type!');     

error is also intermittent, something is happening in the code that is causing the image to become malformed.