Not every component is a suitable candidate for registration-free COM. A component is not a suitable if any of the following are true:

The component is an out-of-process server. EXE servers are not supported; only DLLs are supported.

The component is part of the operating system, or is a system component, such as XML, Internet Explorer, or Microsoft Data Access Components (MDAC). You should follow the redistribution policy of the component author; check with your vendor.

The component is part of an application, such as Microsoft Office. For example, you should not attempt to isolate Microsoft Excel Object Model. This is part of Office and can only be used on a computer with the full Office product installed.

The component is intended for use as an add-in or a snap-in, for example an Office add-in or a control in a Web browser. Such components typically require some kind of registration scheme defined by the hosting environment that is beyond the scope of the manifest itself.

The component manages a physical or virtual device for the system, for example, a device driver for a print spooler.

The component is a Data Access redistributable. Data applications generally require a separate Data Access redistributable to be installed before they can run. You should not attempt to isolate components such as the Microsoft ADO Data Control, Microsoft OLE DB, or Microsoft Data Access Components (MDAC). Instead, if your application uses MDAC or SQL Server Express, you should set them as prerequisites; see How to: Install Prerequisites with a ClickOnce Application.