Visual-studio – Issue: VS2005 not working with VSTO for Office 2007

Office 2k3 Standard is not compatible with VSTO; upgrading from 2k3 standard has likely left something in your registry.

This thread suggests that even moving to 2k7 doesn't give compatibility in this case! How about creating a new user profile?

Here are some questions for troubleshooting:

• What kind of add-in are you developing? A Shared Add-in or a VSTO? If VSTO which version?
• What OS are you using? Vista can be tricky...

• Check the LoadBehavior of your add-in in the Registry. You find the value either in

  HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Office\Word\Addins\<add-in class name>\
  

  or

  HKEY_CURRENT_USER\SOFTWARE\Microsoft\Office\Word\Addins\<add-in classname>\
  

If the value of LoadBehavior is 2 your add-in has been disabled during startup. This happens when Word cannot instantiate the add-in, typically because the add-in throws an unhandled exception, or - much more often - because the add-in is not correctly registered.

Have you checked that the VSTO runtime is correctly installed on the target system?

However, even if you use VSTO, for Word the add-in still looks like a classic COM add-in which is extending the classic IDTExtensibility2 interface. Such add-ins must be registered the following way:

• One of the two registry keys above to tell Word the class name of the add-in plus additional information such as the load behavior and a description

• The class name of the add-in must be registered under

  HKEY_CLASSES_ROOT\<add-in classname>\CSLID
  

• The correct version of the COM component must be registered under (where {xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx} is the guid of the component as specified under HKEY_CLASSES_ROOT\\CSLID):

  HKEY_CLASSES_ROOT\CLSID\{xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx}
  

The following two links might also help you further narrowing down your problem:

HOWTO: Troubleshooting Visual Studio and Office add-ins

Troubleshooting Outlook COM Addins – Using ProcMon