Have found the problem, it is a plugin conflict with this: http://www.semiologic.com/software/external-links/
Shame as this External Links plugin is very useful. Clearly, it is detecting the next / previous links as external ones. Any idea how I might resolve this? I need my external links to open in new windows, any idea how I set this globally (marking each one a nofollow / blank is not possible). Thanks
Tim, London