I have used Excel 2007 for about a year, recently I have noticed this condition: When I open excel to an excel file I have used many times make changes or not I close the file by clicking the X in the upper right corner OR file/exit a blank Excel screen comes up with a warning note that Excel closed wrong and windows is searching for the cause it never finds anything but a blank Escel comes up to create a new file, I must close it with no warnings that it was closed incorrectly.

Any Ideas for what is causing this??