Unrecoverable build error
This is one of the more common errors seen when building Setup projects. It is usually caused by one of the following issues. Visual Studio generates this error when it cannot determine the exact reason for a critical failure and is unable to continue building. If the following suggestions do not work, you should contact customer support or look for a related KnowledgeBase article.
To correct this error
Duplicate folder names in your projects can cause this error. Give the folders unique names.
Unregistered or incomplete registration of Mergemod.dll can cause this error. Re-register Mergemod.dll. From the Start menu, click Run, and then in the Run dialog box, type Regsvr32 <path>:\Mergemod.dll.
Multiple open windows in the Visual Studio IDE can cause this error. Close the windows and try rebuilding the setup project.
Upgrading from the Beta 2 version of Visual Studio 2005 can cause this error. Reformat your computer and reinstall Visual Studio.