This issue affects eNSP 1.2.00.390 with VirtualBox 5.0.16 - 22 running on Windows 10 version 1607 (Anniversary update).
After Windows 10 is updated to version 1607 (Anniversary update), emulated devices stop working in eNSP.
Sometimes the devices are stuck in the loading process, oher times eNSP shows Error 40.
Using the troubleshooting steps provided in eNSP help for device failing to start do not give any results.
The next step was to investigate Windows 10 Anniversary compatibility with eNSP and required components (VirtualBox, Wireshark, WinPcap).
It was discovered that the version of VirtualBox 5.0.16 included with eNSP 1.2.00.390 is not fully compatible with Windows 10 1607 (Anniversary update).
On the other hand, the latest release for VirtualBox v5.1 is not compatible with eNSP 1.2.00.390.
A compatible version of VirtualBox branch 5.0 is needed. Versions 5.0.24, 5.0.26 and 5.0.28 are confirmed to be working.
If eNSP is not yet installed, first install a compatible VirtualBox, then install eNSP without the included VirtualBox.
If eNSP has already been installed, first uninstall VirtualBox 5.0.16 then install a compatible version.
If needed, remove the old base images from VirtualBox and register devices from eNSP Menu>Tools?Register device.
Check compatibility with next release of eNSP.