In the class CMFCToolBarImages there are two static HDC variables named hDCGlyphs and hDCMono. Failure to clear these static variable can cause an ActiveX control's host to fail to shut down.
I discovered this issue in an ActiveX control that used CMFCVisualManagerOffice2007. Use of this VisualManager will make it impossible to cleanly shut down the host of an ActiveX control that employs it because invocation of the GdiplusStartupOutput::NotificationUnhook function will cause GDI+ to launch a thread. GdiplusShutdown will then not fully shut GDI+ down and the host process will remain resident.
Note: I was able to work around this problem by calling CMFCToolBarImages::CleanUp() prior to calling GdiplusStartupOutput::NotificationUnhook.