HTTP & HTTPS issues with multisite wordpress

I have setup a multisite wordpress installation, using paths (not subdomains).

I am having the following issue between HTTP and HTTPS. When ever I goto a link (eg, <site>/pagename), the page works fine in HTTPS, but I get a 404 in HTTP. This seems to be the case for every page (minus the frontpage).

I am not entirely convinced that this a url-rewrite issue, since other applications (drupal), do not seem to experiance this issue. Is there a setting somewhere to resolve this (or do I need to add something to my .htaccess file?)

Thanks,
Steven