TFS Build and password protected strong name keys

A problem that I and many others have had occurs whe you use TFS Build to build projects that are signed with a password protected strong name key. When the project is built the first time in Visual Studio a dialog pops up prompting for the password. In an automated build process this dialog cannot be displayed, which results in the following error:

C:\WINDOWS\Microsoft.NET\Framework\v3.5\Microsoft.Common.targets(1805,7): error MSB4018: The "ResolveKeySource" task failed unexpectedly.
System.InvalidOperationException: Showing a modal dialog box or form when the application is not running in UserInteractive mode is not a valid operation. Specify the ServiceNotification or DefaultDesktopOnly style to display a notification from a service application.
 at System.Windows.Forms.Form.ShowDialog(IWin32Window owner)
 at System.Windows.Forms.Form.ShowDialog()
 at Microsoft.Build.Tasks.ResolveKeySource.ResolveAssemblyKey()
 at Microsoft.Build.Tasks.ResolveKeySource.Execute()
 at Microsoft.Build.BuildEngine.TaskEngine.ExecuteInstantiatedTask(EngineProxy engineProxy, ItemBucket bucket, TaskExecutionMode howToExecuteTask, ITask task, Boolean& taskResult)

To work around this issue, follow these steps:

1. Log on to the build server with the account used for tha automated builds (normally the TFS service account).
2. Open a command prompt and navigate to C:\WINDOWS\Microsoft.NET\Framework\v3.5\
3. Run msbuild "C:\Project\Project.sln" /t:rebuild for each project (.csproj) or solution (.sln) that contains password protected strong name keys.
4. Enter the password when the prompt is displayed. The certificate is then saved in the certificate store for the service account.
5. Restart the Visual Studio Team Foundation Build service.

When the certificates have been read into the certificate store for the build account an automated build should work as expected. This same solution is posted in several blogs, but most posts do not mention that a restart of the build service is required. However I had to do that before I got the automated builds to work.