How to fix the issue: An error occurred while validating. HRESULT = '80004005'

The exception:

An error occurred while validating. HRESULT = '80004005'

when you build a setup project by Visual Studio 2008, you may got the exception, it may caused by that you have one of a project property setting conflict,change all the involved projects from ToolsVersion="4.0" to ToolsVersion="3.5".

The steps:

1. right click each project in solution view, click "unload project"

2. change the ToolsVersion="4.0" to ToolsVersion="3.5"

3. reload project.

4. rebuild all and the setup project.