Looks like Wine doesn't implement the function called by .net's System.Security.Principal.WindowsIdentity.get_Group method, maybe NetUserGetGroups(). Please file a bug report, and include the output of your app as an attachment, e.g. do wine foo.exe > log.txt 2>&1 where foo.exe is the name of the app you're running, and attach log.txt. Be sure to use the latest Wine (1.3.6) when doing the test, or at least mention which version you are using. I think the app you're running is http://support.oticon.com/com/Pro/OurProducts/Software/FittingSoftware/index.htm and sadly there's no trial version, so it's hard for use to try it ourselves.
