So, I spun up a Debian guest VM on my Arch host machine using Virtualbox 4.3.8. After running all necessary tests and stabilizing the server environment on the VM, I moved the entire VM to my Debian host machine running Virtualbox 4.2.1. The VM runs just fine for about an hour and a half, then the VM freezes. No SSH, no ACPI shutdown, no response. I just have to power off the VM and restart. Then I get a good hour out of it before it freezes again.
I really have no idea what the real problem is considering the guest ran just fine on my dev machine (Arch w/ Vbox 4.3.8) host for almost 2 months without a single hiccup. I'm assuming it could have something to do with running a new (4.3.8) VM guest image on and older (4.2.1) Vbox host. Is that a possibility?
Note: I'm running 4 other servers in a Docker Vbox VM on the same Debian box with Vbox 4.2.1 just fine. Those servers have been (and still are) running just fine for the last 4 months.