Comment 5 for bug 1398406

Looks like it's to do with virtual networks being tied to affinity groups. I left a comment a while ago about not using Location when creating virtual networks:

// Note: the Azure documentation recommends to use
// Location when creating virtual network sites.
// We have historically used Affinity Group, and
// have observed intermittent issues when switching.
// http://msdn.microsoft.com/en-us/library/azure/jj157100.aspx

It would seem there's a guaranteed failure for D-series instances when using AG, so I'll switch it over again. It could have been that there were problems in the transitional period.

One problem that we'll have is that existing environments will not be able to provision D-series machines. We'll have to filter them out if the vnet has an affinity group.