For me, enabling VT (Virtualization Technology) on BIOS solved this insufficient memory issue. Now, VMM works just fine.
Jun's 1.02B, 3615xs, i3-4130, Baremetal.
Make sure you enable VT(virtualization technology) in your BIOS.
I had the same problem and this solved it.
Jun's 1.02B, DSM 6.1.3.U7, DS3615xs, i3-4130.