- Make sure you have the VISTA Playonline Viewer from playonline.com and that it is the correct region (NA, EU, JP).
- Disable Secure Desktop.
- Right-Click > Run as Administrator.
- Remove any scripts from the init which are set to auto-load (might want to try removing the plug-ins too, you can load them when you're in game.
- http://www.windower.net/forums/viewtopic.php?t=10267&postdays=0&postorder=asc&start=0
My Windower works just fine on Vista Home Edition.