Silverlight 4: Resolving Microsoft.Silverlight.CSharp.targets was not found?

I've been upgrading some Silverlight 3 apps to Silverlight 4 in Visual Studio 2010. My Silverlight 3 apps open fine in Visual Studio, but SL4 apps don't, with the following error:

C:\Path\To\MyProject.csproj : error : Unable to read the project file 'XNTVOD.AdminClient.csproj'. C:\Path\To\MyProject.csproj(593,3): The imported project "C:\Program Files (x86)\MSBuild\Microsoft\Silverlight\v4.0\Microsoft.Silverlight.CSharp.targets" was not found. Confirm that the path in the <Import> declaration is correct, and that the file exists on disk.

I had a problem with older VS Silverlight components and recently uninstalled most of the SL components, and right now in Add/Remove programs I have:

1. Microsoft Silverlight
2. Microsoft Silverlight 3 SDK
3. Microsoft Silverlight 4 Toolkit April 2010

The <import> declaration looks like this for the SL4 project:

<Import Project="$(MSBuildExtensionsPath32)\Microsoft\Silverlight\$(SilverlightVersion)\Microsoft.Silverlight.CSharp.targets" />

That folder, C:\Program Files (x86)\MSBuild\Microsoft\Silverlight\v4.0 only has two files in it:

Microsoft.Ria.Client.targets

Microsoft.Ria.Client.VisualStudio.targets

What Silverlight development component am I missing in particular? I see a bunch of different options, from Silverlight 4 SDK Beta to VS Tools for Silverlight 4 and a bunch of others. I don't want to install stuff that will get me right back to the situation I had before this one with outdated components.

Looks like this is the missing piece...

Silverlight 4 Tools for Visual Studio 2010

The file that's missing ships in the Silverlight 4 SDK. You can either install just the Silverlight 4 SDK, or re-install the entire Silverlight 4 Tools for VS2010 package (which will re-install the developer runtime, SDK, a hotfix for VS2010, the Silverlight 4 Tools package, and WCF RIA Services).

You may get this with Silverlight version 4 projects when trying to open in version 5 if version 4 bits are not on that machine. What has worked for me (after several hours of trying everything) is to edit the csproj file and change the silverlight target version

<TargetFrameworkVersion>v4.0</TargetFrameworkVersion>

From 4 to 5

This worked well for me...also had to install Silverlight 4 Developer runtime

Afer many tries, what worked for me was:

1. go to add or remove programms
2. remove all silverlight versions installed (4, 5 or even if version is not specified remove it too!)
3. install Silverlight 4 SDK
4. install Silverlight 5 for developers Finally opened the project in VS 2010 SP1

A previously working installation can break when you install a new version of TFS on the server (or whatever it was that messed with my MSBuild).

My 'targets' files had disappeared from C:\Program Files (x86)\MSBuild\Microsoft\Silverlight\v5.0 on Server 2012 and reinstalling the tools.

I believe it may be possible to just copy the targets files from another machine but not 100% sure.