I imagine you had the same issue I had. The imbue dropped your sovereign's essence down far enough that he could no longer sustain all the enchantments he had going. That resulted in the crash to the desktop.

The temporary solution is to dispel one of your enchantments and then do the imbue. Save first, of course, in case that is not your issue.

Ah so enchantment slots are the issue... Does anyone know how many enchantments slots you get? I've got a feeling its half you essence (rounded up or down?), imbue uses 3 essence so do you have to drop one enchantment or 2?