[fedora-virt] Ubuntu KVM goes 100% cpu?

[Tom Horsley]

I've just tried to install a couple of different ubuntu
variants into KVM virtual machines, (ubuntu 14.04.01
and linux mint 17 xfce).

At some point they always seem to jump to 100% cpu
and hang forever, or sometimes not forever, but when
they come out of the 100% mode, the screen rendering
is hopeless with most of the letters left out of
words.

Does this sound familiar to anyone?

I'm using spice/qxl video and virtio disks. Virt-manager
is running over a somewhat high latency remote connection
with ssh protocol.