MS Windows Home Server

I have been running whs for quite some time and have worked through many issues, this one is new. I have six machines backing up to whs, xp's and vista's. I completely stripped the hard drive on one of the vista machines and reinstalled vista 64. After this all machines still back up except the 64, it gives me Backup Sever Failed everytime. Any ideas.

I have the same issue. I just upgraded my four PC's from Vista to Win 7. Two of them are 64 bit machines. One would not take the upgrade so I had to do a new installation. Since then, I am getting a backup failure message. I am thinking it is because I kept the computer name the same and WHS is trying to do an incremental backup and that is causing an error. I am going to delete all previous backups and see if that makes a difference.