We just upgraded to Office 2013 and we're experiencing the same issue as Marko detailed in his original post. It's not a row limitation issue as it happens regardless of the amount of rows. We've noticed it only occurs when you already have an existing spreadsheet open. If you are exporting to Excel and you don't have any Excel files open, it works fine. We're troubleshooting with our infrastructure team now and will add another post if we're able to resolve it. Thanks.