Plugin and Firefox 6 mismatch

I have just put up a new WP site and the Membership plugin 2.0.6 on Wordpress 3.2.1 doesn't work with Firefox 6.0 even in Safe Mode at least for Twenty Eleven and Twenty Ten themes. The Dashboard is visible as normal.

It works for other sites that I have.

The plugins I have active are:Bad Behavior, en-GB localisation, Subscribe2, Twenty Eleven Theme Extensions and UK Time. There are others but they are not activated.

I switched all plugins off and it works and switched them on one by one. The only one to repeat the problem is Membership. It works with Chrome, IE and earlier Firefoxes. I don't know whether this is a plugin or browser issue.

I have switched Membership off for the moment.:slight_frown:

Has anyone seen this before?