If the VM's were working and then all failed, and you are running on a Windows host, one might suspect a MS update to the host. You might look at the update history for similar dates. I would also scan the VMware log to see if there is something there pointing to a problem.
Another thought is hypervisor conflicts, many posts here about that. Personally, I run all VM's on a Linux host with accelerated 3D off and have few problems.