GAH - "unable to build project output 'content files from WebApplicationName"

I'll split this post into a short/long story in case your searching for any tips on how to fix it and don't wanna hear me rant about it.

Short story

* Error on setup build "unable to build project output 'content files from WebApplicationName"
* Followed Mr Hanselmans instructions at http://www.hanselman.com/blog/VisualStudioMSIProblemsUnableToBuildProjectOutputGroupContentFilesFromSOMEWEBActive.aspx
* Edited the project file - removed all content references
* Readded each content file in Visual Studio.
* Everyone's happy

Long story

Alright, so I'm sitting at work. Happily coding in VS2010, creating a small web-app for my client. Following the corporate install routines and creating a Web Setup project. Everything is perfect. With less than an hour left on the project it all goes to %¤#%.

My setup project doesn't build anymore. It just keeps saying "unable to build project output 'content files from WebApplicationName". Why, oh why can't you just print out the name of the file that is missing?

A quick internet search brought me to Hanslemans blog, a post from June 22, '04. You would think they would have patched this and at least created a better error message in 9 years?

http://www.hanselman.com/blog/VisualStudioMSIProblemsUnableToBuildProjectOutputGroupContentFilesFromSOMEWEBActive.aspx

Yup, files we're missing on disk. Thinking back it might have been when I tried the Install/Uninstall option you get when right-clicking your setup project.

Restored the files again, but STILL got the error above. Spent another hour painfully checking each file in the project files content group. File by file... Nothing missing, it's all on disk.

Recreated the setup project. Still the same error. Restored my code to a point in time where I know that it worked. Still the same error.

What I ended up doing was deleting every content reference in the project file and readded them in Visual Studio. Seems to work now... For the moment...