c'est ici http://blogs.technet.com/rakeshm/archive/2008/05/20/scvmm-2008-beta-and-the-hyper-v-rc1-release.aspx

 .....Due to some necessary and important interface changes made by the Hyper-V team, the recently released beta of SCVMM 2008 doesn't work correctly with Hyper-V RC1.