Vista and Visio
Visio 2007 has an incompatibility with Vista that I have seen many responses too, but most miss being a complete solution.
If your Visio 2007 program refuses to close, or closes with an error, the problem is most likely to be caused by the Send to Bluetooth COM add-in. Disabling it requires that you run Visio as administrator, which in turn can't be done with the normal shortcuts. Instead, go to the Office12 folder (C:\Program Files\Microsoft Office\Office12 in most cases) and right click on the Visio.EXE program and choose "Run as Administrator". Then go to Tools->Trust Center in the menu, then select the "Add-ins" tab. Finally, in the Manage: combo box, set it to "COM Add-ins" and click go. You can now uncheck "Send to Bluetooth" and then confirm all the dialogs along the way.
Vista will now close as expected.