Chris,
I hate to be the bearer of bad news, but it looks like your site has been hacked. There is an iframe that is being inserted above your content and that’s actually what’s causing the layout trouble.
Sometimes hackers will hide their malicious code inside a plugin. Because the “Hello Dolly” and “Akismet” plugins are shipped with every WordPress installation, they are common places to hide code.
You might try disabling all your plugins and see if that fixes the issue. Hopefully it will as that’s the easiest fix. If it doesn’t then it’s possible it’s been added to the theme. You can see that by going to the appearance section and selecting edit to open up the theme editor. From the list of files on your right, choose header.php. Make sure it starts off like this:
<!DOCTYPE html>
If there is anything above that, delete it and save your changes. If you don’t see anything there, then look inside the file named functions.php. It’s possible to place the malicious code there too.
The last option would be for it to be inside your database. I really suggest trying out a plugin called Backup Buddy for that. It allows for easy backups of your site and also has a malware scanner built in.
Let me know if you have any trouble,
Bill