I have a installable which creates a shortcut icon on the desktop at the end of install. The shortcut appears with the correct icon on all operating systems except longhorn. The icon that appears on longhorn is blank. However, am manually able to create the shortcut with the correct icon. Does anyone know why this is happening? The icon is taken from an exe file. Is there any file type sepecifications for icons in longhorn? Also, am using installshield 11 for building the installable.

Which version are you using? You should try a later build since I believe this was fixed in a later release.