Starting/stopping virtual machines in a group

I'm able to stop all VMs in a group by selecting the group in the "Assets-All User Defined Groups" pane

and hitting the "Shutdown/detach" button, but not able to start them all together because the "Start" button is grayed out

(it only becomes available when selecting individual VMs).

Another question is, how do I start/stop all machines in a group that consists of both Sparc and x86 VMs?

In this scenario both "Shutdown/detach" and "Start" buttons are unavailable.

Is there another way of starting/stopping a bunch of VMs other than assigning them to a group?