dear jacku
yes i have changed images and thumbnail path in gallery.xml which should be in root of your pixelpost and it had resolved the issue.
just change that value to your root relative path and it will resolve the problem..
e.g.
if your pixelpost is
www.yourdomain.tld/pixelpost/gallery.xml
then your path should be
<thumbnail_dir>./thumbnails/</thumbnail_dir>
<image_dir>./images/</image_dir>