Visual Studio 2010 Service Pack 1 Update, KB2529927, released fixing VS2008 -> VS2010SP1 Setup Project Migration GUID issue...
"Migrating setup project from VS2008 to VS2010SP1 changes component GUIDs, which causes upgrades to fail
Date Published: 8/30/2011
Change Language: Chinese (Simplified) Chinese (Traditional) English French German Italian Japanese Korean Russian Spanish
KB Articles: KB2529927
VS10SP1-KB2529927-v2-x86.exe 2.0 MB
When you install the .msi file that is created from the Visual Studio 2010 SP1 Setup project, the .msi file determines that the GUID has changed. Therefore, the .msi file removes the files and registry keys for the installation path by using the sequence of the project. This issue occurs because a different hashing algorithm is used to create the Globally Unique Identifiers (GUIDs) in Visual Studio 2010 SP1.
To resolve this issue, apply this hotfix, and then set the new BackwardCompatibleIDGeneration property to True before you build the project.
This hotfix introduces the BackwardCompatibleIDGeneration property. By default, this property is set to False. Before you build the Setup project in Visual Studio 2010 SP1, you have to explicitly set the BackwardCompatibleIDGeneration property to True
I've run into this (and thought it was something stupid I was doing. Given that I "do stupid" allot, that wouldn't surprise me... lol ;)