C:\WINDOWS\Microsoft.NET\Framework\v4.0.30128\Microsoft.Common.targets(1835,9): error MSB4018: The “GenerateResource” task failed unexpectedly.
C:\WINDOWS\Microsoft.NET\Framework\v4.0.30128\Microsoft.Common.targets(1835,9): error MSB4018: System.DllNotFoundException: Unable to load DLL ‘FileTracker.dll’: A dynamic link library (DLL) initialization routine failed. (Exception from HRESULT: 0x8007045A)
C:\WINDOWS\Microsoft.NET\Framework\v4.0.30128\Microsoft.Common.targets(1835,9): error MSB4018: at Microsoft.Build.Shared.NativeMethodsShared.InprocTracking.StartTrackingContextWithRoot(String intermediateDirectory, String taskName, String rootMarker)
C:\WINDOWS\Microsoft.NET\Framework\v4.0.30128\Microsoft.Common.targets(1835,9): error MSB4018: at Microsoft.Build.Utilities.FileTracker.StartTrackingContextWithRoot(String intermediateDirectory, String taskName, String rootMarkerResponseFile)
C:\WINDOWS\Microsoft.NET\Framework\v4.0.30128\Microsoft.Common.targets(1835,9): error MSB4018: at Microsoft.Build.Tasks.GenerateResource.Execute()
C:\WINDOWS\Microsoft.NET\Framework\v4.0.30128\Microsoft.Common.targets(1835,9): error MSB4018: at Microsoft.Build.BackEnd.TaskExecutionHost.Microsoft.Build.BackEnd.ITaskExecutionHost.Execute()
C:\WINDOWS\Microsoft.NET\Framework\v4.0.30128\Microsoft.Common.targets(1835,9): error MSB4018: at Microsoft.Build.BackEnd.TaskBuilder.ExecuteInstantiatedTask(ITaskExecutionHost taskExecutionHost, TaskLoggingContext taskLoggingContext, TaskHost taskHost, ItemBucket bucket, TaskExecutionMode howToExecuteTask, Boolean& taskResult)
========== Build: 1 succeeded or up-to-date, 1 failed, 0 skipped ==========

just found a nice way of installing Silverlight 4 beta for Visual Studio 2010 RC.

http://blog.andrew-veresov.com/post/Enable-Silverlight-4-Tools-in-Visual-Studio-2010-Release-Candidate.aspx