MSBuild problem with .NET Framework 4 RC1 x64

We are experimenting with TeamCity and .NET Framework 4 and have so far been pretty successful using the x86 MSBuild but not the x64 version.

The Build Agent has the following system properties:

We set env.MSBuild to the appropriate .NET version to enable the sln2008 task to compile our .NET 4 solutions.

If we use the x86 MSBuild then the solution will build fine.
env.MSBuild=%system.DotNetFramework4.0_x86_Path%

But if we use the x64 MSBuild (env.MSBuild=%system.DotNetFramework4.0_Path%) then we get the following build error:

Build 'project :: CI Build' #4.0.15.72505 [ci_build]
Started 'Thu Feb 11 14:41:29 GMT 2010' on 'tcagent' by 'Vault'
Finished 'Thu Feb 11 14:41:40 GMT 2010' with status 'ERROR Failure'
TeamCity URL http://teamcity/viewLog.html?buildId=132&buildTypeId=bt44.0.15.72505 [ci_build]

[14:41:24]: bt4
[14:41:24]: Checking for changes
[14:41:29]: Clearing temporary directory: C:\TeamCity.BuildAgent\temp\buildTmp
[14:41:29]: Checkout directory: C:\TeamCity.BuildAgent\work\1140675e932e9582
[14:41:29]: Updating sources: server side checkout...
[14:41:29]:     [Updating sources: server side checkout...] Building incremental patch for VCS root: Vault
[14:41:39]:     [Updating sources: server side checkout...] Repository sources transferred
[14:41:39]: Starting build process in C:\TeamCity.BuildAgent\work\1140675e932e9582\project
[14:41:40]: sln2008 output:
c:\TeamCity.BuildAgent\bin\..\plugins\dotnetPlugin\bin\JetBrains.BuildServer.MsBuildBootstrap.exe @xml C:\TeamCity.BuildAgent\temp\agentTmp\msbuild14127.teamcity.bootstrap.properties
TeamCity MSBuild bootstrap v5.0 Copyright (C) JetBrains s.r.o.
Start MSBuild...
'C:\Windows\Microsoft.NET\Framework64\v4.0.30128\MSBuild.exe' '@"C:\TeamCity.BuildAgent\work\1140675e932e9582\project\project.sln.teamcity.msbuild.tcargs" "C:\TeamCity.BuildAgent\work\1140675e932e9582\project\project.sln.teamcity.patch.tcprojx"'
working dir = 'C:\TeamCity.BuildAgent\work\1140675e932e9582\project'
Microsoft (R) Build Engine Version 4.0.30128.1
[Microsoft .NET Framework, Version 4.0.30128.1]
Copyright (C) Microsoft Corporation 2007. All rights reserved.

MSBUILD : error MSB4016: The build stopped unexpectedly because the "ReusableLogger" logger failed unexpectedly during initialization. Component JetBrains.BuildServer.MSBuildLoggers.MSBuildLoggerImpl was not found

[14:41:40]: Process exit code: 1
[14:41:40]: Build finished



We are using TeamCity 5.0.2.10784 and .NET Framework 4.0 RC1.

Should this be a supported operation (using x64 MSBuild) or is it expected that we can only use the x86 version?