How to fix: "The command you are attempting cannot be completed because the file 'xxx.vdproj' is under source control and is not checked out" when building solutions containing setup projects in VS2010
Today I revisited some old projects under Visual Studio 2010 to carry out some maintenance. The solution file contains a handful of C# code projects, and two Deployment Projects (vdproj). Every time I tried to build, it would succeed but I would be prompted with this dialog for each Deployment Project.
Clicking OK or closing the dialog would prompt another to pop-up, at least a dozen or so times before finally finishing the build.
A bit of digging about (some of the links provided in various forums posts have since become broken) and Microsoft released a hot fix back in April 2011 which you can find here. According to one post, the issue is down to a different hashing algorithm employed by Microsoft for generating GUIDs in SP1 of VS2010.
Any deployment projects created before SP1 and checked into source control will then attempt to update the component GUID and popup this error, although I seem to get this on every build if the .vdproj is checked in, regardless of whether VS2010 SP1 has previously updated the file.
Fortunately installing this hot fix makes the problem go away and stops me having to mash my enter key every time I want to build.