If you have not already registered, you can do so here.
The ACE system has recently been updated to prevent the same user login being used multiple times. This is a security feature to help prevent against fraud within the certification process.
You will need to leave it 10-15 mins, clear your cookies and favourites of the ACE site and enter the site manually into the web browser.
Remember to click the logout button when you are finished with the ACE site and don’t just close the tab/browser.
Test to see if your computer is compatible with ACE with our system checker tool.