Were you able to resolve this issue?
A few things to try for other users encountering such an issue.
1) are you utilizing a recent version of Tableau Desktop? If there was a known issue, verify the issue is not fixed in a more recent version. Tableau has recent versions of 8.1 - 9.0 available here for download: Alternate Download Site | Tableau Software
2) in the case of Microsoft Excel data sources, there are two potential connection methods. The default one for versions 8.2x and above is to utilize the Tableau Excel connector. However, when selecting the Excel file from the open file dialog box, there is a dropdown menu item associated with the "Open" button. Try opening with the "Legacy Connector" to see if the issue exists with the Microsoft connection. The differences between these connectors is documented here: http://kb.tableau.com/articles/knowledgebase/diff-between-jet-default-connection-types
If the issue only exists in one of the connection types and the most recent version of Tableau is installed, please create a support case by going to Product Support | Tableau Software and clicking on "Create a Support Case"
I hope this helps.