The header is messed up. I deleted the INI files in cache and also the .tpl.php files in Smarty. I've deleted temporary internet files and cleared my browser's cache, to no avail.
This is what is displaying in Chrome:
Post site link we can probably help better then
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It's a newly installed vanilla forum that I imported the data from phpBB3. It's completely stock.
It looks fine until you login to the forums with my admin account, otherwise I would post the link. Regular users look fine.
Looks like certain elements are not styled correctly for guests. Cannot help without link and or test account. As i dont use this theme.
It looks fine with a moderator account or user, but with the Admin account, there are extra links on the top header, which I think is pushing it to a new line in Chrome.
Admin has Dashboard and Activity links. Everyone else does not have those, so it appears to display correctly. I used Chrome to inspect element and deleted the Dashboard link and everything gets moved up to where it should be.
Not sure how to fix this without breaking the other browsers.
In firefox use firebug inspect element u think is causing trouble. Usually things like this a height attribute has been missed. Webkit isnt as forgiving as moz
I didn't see anything checking. I think maybe making the text smaller, or making the header stretch all the way across the top of the page will fix it. People with longer usernames will most likely run into this same issue.
The problem is the Mark All Viewed plugin.
I recommend removing the Mark All Viewed menu from the header to the sidebar or elsewhere. You do that by editing the plugin.