eMule is an application that hasn't been updated for almost 4 years. The compatibility of the latest release with Windows applies to the following versions: 95, 98, ME, 2000, and XP.
However, the developers updated the application to an alpha state making the version to 0.50a which is compatible with Windows 7 an 8. Try to download this version and make sure that you install the application with Administrator rights.
