This plug-in seriously screwed up my template. I'm not an expert, but thank god I managed to work out that it was this plugin causing the problems.
When using :
<?php the_excerpt(); _e('<p><a href="'.get_permalink().'">Read More About - '); the_title(); _e('</a> »</p>'); ?>
Any posts that had NextGEN gallery would display the full post, not just the excerpt. Also, it screwed up the site layout so my sidebar would be shoved to the bottom of the page and text form articles would spill into where the sidebar should be.
I'm using a premium theme from StudioPress called "Streamline" and when I posted about this problem on their forum they told me that NextGEN Gallery was injecting invalid xhtml.
My site is located at http://www.techietalk.co.uk but I've disabled NextGEN for now because I can't afford to have my site ruined. I'd love to be able to use NextGEN though if a fix for this problem can be found.