Login needs two tries every time!

When I log in, it doesn’t work the first time, but when you put your email address in again, then it works. I am getting an email as admin telling me it’s been successful after the first attempt. I want to use this facility for people who are technophobes, so it needs to be as easy as possible! I have used the plugin before on a different site with no problem.

The page I need help with: [log in to see the link]