Belgium eID 1.0.16 extension is responsible for d3d9window message
Because I have spend hours looking for a solution and finally found it, I thought I would share it here so others with a the same problem may find this.
After installing the necessary addon for the Belgian Taxonweb application, the Belgium eID extension, Firefox did not close anymore. Well the window closed, but the process remained active. When shutting down a message stated that a D3D9Window was still active.
After disabling the Belgium eID extension, all troubles went away...
Firefox 13.0.1 on XP sp2
Wšě wotmołwy (2)
tomvdp, thanks for sharing your solution for your problem with us.
To complete this: merely disabling the extension is not enough. I had to completely uninstall the Belgium eID application. Even starting Firefox in safemode resulted in the same problematic behaviour.