how to bring VirtualBox out of 'Guru meditation'

I have been using Oracle Virtualbox for work for quite a few years now. This time around I have a few relatively big virtual machines running. A Netapp simulator and a UCS platform Emulator. I keep switching between the two, by pausing one to free up memory to work on the other.

Yesterday, the UCS one suddenly can not be started again from the Virtualbox Manager GUI. All possible actions for the vm are grayed out, except that I could review logs. 

Under the vm icon, it says 'Guru meditation'. The mouse-over hint said 'session locked'.  

The actual directory looks pretty clean. The Logs/VBox.log indeed has an entry confirming this unfortunate 'guru meditation' state.

41:15:26.089214 UIMediumEnumerator: Machine (or snapshot) event processed, ID = d2b17907-9bef-4e1d-b755-d6be33e5570a

41:15:26.089683 UIMediumEnumerator: Machine (or snapshot) event received, ID = d2b17907-9bef-4e1d-b755-d6be33e5570a

41:15:26.089856 UIMediumEnumerator:  Old usage: 0210f54c-ea12-4a15-bc4d-f8fa690759a8, 658b6fcb-ee59-4065-abd4-c3aeb1eab3a8, 6d3ed09f-42cd-4b36-8652-b4a75e8181bd, 7b83e1e3-ffc2-445d-a9fc-9d6586833b4e, 8589d5fd-4ff3-4c80-b915-7cee87a2e974, e6964c46-790b-4aff-82fb-b22a83792882, f623a9aa-4b0c-44a0-b34c-34d9a3f09dd6, fea35c17-bc46-4d31-84b0-08f4620e7cc4

41:15:26.101502 UIMediumEnumerator:  New usage: 658b6fcb-ee59-4065-abd4-c3aeb1eab3a8, e6964c46-790b-4aff-82fb-b22a83792882, f623a9aa-4b0c-44a0-b34c-34d9a3f09dd6, 8589d5fd-4ff3-4c80-b915-7cee87a2e974

41:15:26.101557 UIMediumEnumerator:  Items excluded from usage: 7b83e1e3-ffc2-445d-a9fc-9d6586833b4e, fea35c17-bc46-4d31-84b0-08f4620e7cc4, 0210f54c-ea12-4a15-bc4d-f8fa690759a8, 6d3ed09f-42cd-4b36-8652-b4a75e8181bd

41:15:26.113783 UIMediumEnumerator: Machine (or snapshot) event processed, ID = d2b17907-9bef-4e1d-b755-d6be33e5570a

41:15:26.135516 UIMediumEnumerator: Medium-enumeration finished!

41:21:23.219316 ERROR [COM]: aRC=VBOX_E_INVALID_VM_STATE (0x80bb0002) aIID={8ab7c520-2442-4b66-8d74-4ff1e195d2b6} aComponent={Console} aText={Invalid machine state: GuruMeditation}, preserve=false

I made a copy of the virtual machine directory, embracing for the worst.
Then it dawned on me that I may be able to bring it out of 'session locked' state via CLI, namely, VBoxManage. 

Viola!

Mac:/Users/jack/VirtualBoxVMs$ VBoxManage controlvm ucspe resume

VBoxManage: error: Cannot resume the machine as it is not paused (machine state: GuruMeditation)

VBoxManage: error: Details: code VBOX_E_INVALID_VM_STATE (0x80bb0002), component Console, interface IConsole, callee nsISupports

VBoxManage: error: Context: "Resume()" at line 118 of file VBoxManageControlVM.cpp

Mac:/Users/jack/VirtualBoxVMs$ VBoxManage controlvm ucspe poweroff

0%...10%...20%...30%...40%...50%...60%...70%...80%...90%...100%

As soon as VBoxManage finished executing, all the grayed-out actions became available again on the GUI for this vm. I started it. 

The virtual machine came up just fine. What a relief :-)

In case more specifics help somebody, I am running Virtualbox v3.4.8 on Mac OS X 10.9.2 (Maverick). The two VMs in question are Linux 2.6 and FreeBSD.