Hi Lisa,
This is happening because the XSF failed to upload properly to SharePoint. To fix this problem, you should just go the the SharePoint form library. Click modify settings and columns. Click on Edit Template to open the form in the InfoPath Designer. No, add a space somewhere in the view and delete it - to make save update. Type ctrl-S to save the form template back to the server. Make sure there are no errors. If there are errors, simply try to save it again. Sometimes it takes a few attempts if there is network trouble. Now, go back and try to open the XML file.
If you still have a problem, it must be because the solution is corrupted in some way. You can try to extract the files in the XSN by renaming the extension CAB and using WinZip to extract and then open up the XSF and see what is inside it.
Good luck!
Patrick Halstead
Project Manager at Qdabra