vboxmanage updagega cli crashes guest vboxservice

[Southdave]

I am running v5.1.8 along with the latest guest additions. My host is windows 8.1 64bit, my guests are a mixture of windows clients (32 and 64 bit) and a mixture of windows servers (32 and 64 bit) and i have the same issue with all of them.

i can start the vms, issue guestcontrol and guestproperty commands and they all run perfectly. However when i use the command:

vboxmanage.exe guestcontrol "vm name" updatega

it sits there waiting to talk to my guest vm and then times out with a bunch of errors about not being able to communicate with the vm.

Example errors are

ERROR [COM]: aRC=VBOX_E_IPRT_ERROR (0x80bb0005) aIID={13a11514-402e-022e-6180-c3944de3f9c8} aComponent={GuestWrap} aText={Could not open guest session: VERR_TIMEOUT}, preserve=false aResultDetail=0
ERROR [COM]: aRC=VBOX_E_IPRT_ERROR (0x80bb0005) aIID={13a11514-402e-022e-6180-c3944de3f9c8} aComponent={GuestWrap} aText={Could not open guest session: VERR_NOT_FOUND}, preserve=false aResultDetail=0

Searching around didnt yield any help and it was only when i looked closely at the guest did i notice that the vBoxService crashed.

I ran the service in the foreground using:

vBoxService.exe -f

and even with verbose does not produce any error in the console window, but does generate the following in the event log:

Faulting application name: VBoxService.exe, version: 5.1.8.11374, time stamp: 0x5806294f
Faulting module name: VBoxService.exe, version: 5.1.8.11374, time stamp: 0x5806294f
Exception code: 0xc0000005
Fault offset: 0x0004e060
Faulting process id: 0x148
Faulting application start time: 0x01d229ee825251a2
Faulting application path: C:\Windows\System32\VBoxService.exe
Faulting module path: C:\Windows\System32\VBoxService.exe
Report Id: 3496c096-95e2-11e6-b2e6-08002785e35e

Any help really appreciated to debug and get updating of the guest additions working from the host cli (as it appears a few people are experiencing these issues).