I have this bug in my daily opera. The second Opera portable has the same error. But already the third portable - no. And in it I have 27 cookies in use on this site. In the main Opera - one cookie, in the third Opera protable - 14, but the page does not look as it should.
@dusty87 The Continue anyway item is hidden under the Details button. But in general ... is your clock set properly? If the date (especially the year) is off Opera may conclude the certificates are incorrect - either not supposed to be in use yet or expired. Either one will get that result.