I can confirm that the issue looks fixed using 3.13.0-44.73~precise1 from precise-proposed.
I made more than ten reboots with the new kernel installed on VMs and all were successful. Then I switched back to the previous 3.13.0-43.72~precise1 and VMs boot failed at the first trial. Again back to propose 3.13.0-44.73~precise1 at VM were booting fine.
I'm not using Trusty on these AMD machines so I cannot test it. But the kernel is the same as precise so the issue should be fixed also on Trusty.
I can confirm that the issue looks fixed using 3.13.0- 44.73~precise1 from precise-proposed.
I made more than ten reboots with the new kernel installed on VMs and all were successful. Then I switched back to the previous 3.13.0- 43.72~precise1 and VMs boot failed at the first trial. Again back to propose 3.13.0- 44.73~precise1 at VM were booting fine.
I'm not using Trusty on these AMD machines so I cannot test it. But the kernel is the same as precise so the issue should be fixed also on Trusty.