Unable to apply publish properties for item “ApplicationCode\SystemNames.xml”

Solved with thanks to:

http://stackoverflow.com/questions/9284375/unable-to-apply-publish-properties-for-item-x

“It appears that the issue is related to ClickOnce. Navigate to the project, right click on it and click on properties. Go to the Publish tab and click on Application Files. Check the ‘Show all files’ checkbox and scroll through the list of files. Eventually, you will come across the file that has a yellow exclamation point on it. This file is orphaned and needs to be removed. Right click on the file and there should be a remove option.

Now build the solution and the warning should be gone.”