We have an issue where whenever a user tries to move to the confirmation page of an event registration (or contribution) page they are getting the browser message 'Are you sure you want to leave this site' popup.
See https://portal.communityfirstyorkshire.org.uk/civicrm/event/register?id=80&reset=1. Try to complete the form and continue.
Has anyone else seen this issue. There is no custom code on this system which would affect this functionality.