Summary :

Joomla 1.6 & Simple image Gallery Plugin 

Error :

JW_SIG_PRG 

Warning: imagejpeg() [function.imagejpeg]: SAFE MODE Restriction in effect. The script whose uid is 10228 is not allowed to access /var/www/vhosts/.../httpdocs/cache/jw_simpleImageGallery owned by uid 33 in /var/www/vhosts/.../httpdocs/plugins/content/jw_simpleImageGallery/jw_simpleImageGallery/includes/helper.php on line 134 

Solution :  

give permission to write this folder : /cache/jw_simpleImageGallery

if it is not allowed to change file permissions. delete file, and create with the same name, and give write permission