OK!

Unable to cast object of type ‘Microsoft.SqlServer.Management.Smo.SimpleObjectKey’ to type ‘Microsoft.SqlServer.Management.Smo.Agent.JobObjectKey’. (Microsoft.SqlServer.Smo)

This happened on the workstation which runs Vista x64.  I am trying to use it as my primary workstation, but my RDP session to my XP box is nearly always open.

It’s not really a Vista issue, but it’s fun to blame Vista for everything.

The solution is to install SQL SP2 for the client tools on the computer you get the error from.