Server 2012 R2 Host - VMMR0.r0 BSOD

[VBS]

I have a Dell PowerEdge R920
128GB RAM
4 x Xeon E7-4830 (10Core) Processors
6 x 1.2TB 10K RPM HDD in RAID5 with 5TB Useable on my VM Store partition
1Gbit 4 Port Broadcom NIC
Host OS - Server 2012 R2 with all MS Updates

Running VirtualBox 4.3.12 R93733.
The reason for this version is that it is the one that the backup software (StorageCraft) supports for their VirtualBoots. (I have already been in touch with them and they said that as long as they work individually, then it is likely a VirtualBox issue instead).

Hoping someone here can shed some light or put me on the right path.

I have 7 Virtual servers I need to spin up together as they run together on a network. They are all Windows servers. A mix of SBS2011, Server 2008R2, and Server 2008.
I can spin all of the virtual machines up individually, but trying to get them all running at once, fails with a BSOD, of which when I use bluescreenview, it always points back to VMMR0.r0.
I can post logs if that will help, but it seems like it does not actually write a log on the server that crashes the host (random as to which one).
I start up the first VM (thePDC), and when it gets to the login screen, I start the next server. I have tried the following 6 in different orders to see if that makes a difference, but it is random. Sometimes it crashes on the second one, sometimes the 5th, but I have never been able to get them running all 7 at once.
Calculating all the RAM I have allocated, I still have plenty. I have allocated a total of 96GB of RAM out of the 128GB available.
Calculating the CPU's I have allocated, I still have some left. I have allocated a total of 29CPUs from the 40 I have available.

I'm no pro at VirtualBox or virtualization, so please bear with me if I'm doing something glaringly wrong.

What is odd, is that we used to run these VM's on a much less robust setup. It ran all servers, albeit extremely slowly due to the lack of sufficient resources.

Thank you

[mpack]

VM log file please, for the failed session of the failed VM.

Minimum information needed for assistance.

[VBS]

For, but they might not be any good, since the last log file is blank as it seems to crash before it can write a log file.
In this instance the servers were started in the following order:
serverqv1, serverqv2, serverqvts1, and then when starting adventdb01 the host crashed.

This isn't always the sequence. It has happened with different orders. Serverqv1 is the PDC of the group of servers, so I always start it first, and it seems to run fine. Picking and choosing the rest of the 6 servers ends up in the host BSOD.