Not only is the new user interface in Office 2007 one of the biggest usability steps backwards I've ever seen in a Microsoft program, the implementation of the new look seems to have a few interesting "features" like this one:

That's right. This is my Excel window the way it shows up about 70% of the times I launch it. The "feature" auto-enabled itself a few weeks ago and hasn't gone away since. The only solution? Restart Excel a few times and trust the law of probability--praised be my beloved keyboard shortcuts.