The strangest things happen when using Hyper-V…
The temptation is often there to make several changes at one time (such as altering network interfaces, changing the number of virtual processors, etc.) it would appear that if you make a change to the settings of an image during the reboot (I shut the image down as opposed to restarting it to facilitate the change) phase of a feature installation, Windows will just repeatedly reboot until you shut the image down and reset the settings to the original values.
I have no idea if this would be the same for Roles, but it is reproduceable with Features so let’s say “it’s likely”.
Moral? Don’t mess with Hyper-V image settings with a pending reboot!