Keep VMWare from auto-closing my virtual machine

It certainly has nothing to do with the drive itself.

This is most likely caused by the power management settings inside the virtual machine: If your VM is set to suspend or hibernate after a certain idle period, it will trigger a VMware suspend.

Additionally, in your VM settings you have probably enabled the "Close after powering off or suspending" setting in the power options causing the virtual machine itself to close after such an event.

In VMWare Workstation go to:

Edit menu > Preferences > in Preferences window > Workspace tab and make sure that the "Keep VMs running after Workstation closes" option is checked.