I'm running Workstation 12.5 under Windows 10 Pro.
If this is Windows 10 1709 (Build 16299) then the KB4056892 cumulative update changed something with regard to network security that causes this issue.
Before the installation of this update several VMs I run from a NAS share operated without issue. After this update, on two different hosts, the VMs started displaying this behaviour. However for me the occurrences are random with the VMs running without issue for several weeks before having problems for a day or two.
I have SMB1 uninstalled on the hosts so I am using SMB2 or SMB2.1 with my NAS (SMB2.1 is the highest my NAS supports). I do not use a shared network drive – I use the UNC path the access the VMs.