Why is Gmail is not letting me view contacts?

Gmail is not letting me view Contacts. They are there because if I compose a new email it will suggest my contacts in the To box, but when I try to open the Contacts page it just tries for ages and never actually opens.

I'm using Chrome Browser. I have tried to delete Cookies etc to clear out any corruption. This almost worked, but the problem is back. If I use Incognito Mode it sometimes works.