Comment 2 for bug 598335

I just discovered that this was my problem as well though I am using amd64 and lucid. When cgroup-bin is installed all operations involving adding or removing modules fail (modprobe, rmmod). There may be other factors at play but for my system once installing cgroup-bin I can reproduce 100% of the time by running "sudo modprobe aes". Removing the packages fixes the problem.