When we first image an R400 out of the box it will hang at a black screen right after running the sysprep process.
At first I thought it was an updatehal issue but that seems to be ruled out when I commented out the updatehal lines. If a hard reset is performed, the post imaging steps will then continue and successfully complete. Once the post imaging process completes successfully at least once and we reimage again everything runs through. It is only the initial imaging process that black screens and just hangs.