Not sure if this can help. But beware what you call your login page when you create it. As an exemple, the adress myside.com/login normally redirect to mypage.com/wp-login
I use this plugin on http://www.helgesen.se but after the upgrade to WP 3.0 it not working anymore. Is there a update for the plugin?
I solve the problem, it was not NextGEN Gallery that cause problem on http://www.helgesen.se Since I’m running other sites with WP, and after the upgrade to 3.0 NextGEN Galler still works. So I started to search for other problems and I found out that the 301 redirect plugin was the one that cause this error.
Problem solved..