Sorry, didn't notice earlier but I've fixed it now.
It seems as though when you change your email address the system normally sends an email to confirm that it is a valid email address (and gives you a link to click to confirm it or something). It appears that emails are not being sent out at the moment (possibly turned off to reduce server load during recent heavy duty use of the site?)
Anyway, thanks to a PM from Blackrat I've got on the case and all should be OK now - do let me know if it isn't.
Regards,