hi... vm or its disks are still on somewhat open state (ie potentially hung)
try the following.
from service console or management console
vm-support -x (should give you a list of running VMs.. see if you find the one you want to power on and take note of its id number
vm-support -X id
this will promtp you for basic stuff one thing it mentions though is do you want to send a kill signal to the vm... ensure you select yes.
procedure takes about 10 or so minutes and then when finished you should be able to power on vm.
