Not sure how good Opera is for troubleshooting, so for completeness' sake if it were me I'd probably try in Firefox or Chrome. It sounds like some of the session info isn't transferring, so clearing cookies (again, yes), clearing cache, and restarting the browser might work where just clearing the cookies didn't.
Also make sure your computer clock is set correctly. *points to top right corner*
If you've never logged into the wiki before, might have a staffer check your access level to make sure that it's set correctly on the forum side.
Failing that, you'll probably have to PM Vekseid.