Please, try removing the file ForestVRay20.dll from the Max root folder, next reinstall Forest to be sure the DLL was updated correctly. If it doesn't work, i would suggest to try Forest 3.7.2 again to see if there is some difference.
About the winsocks error, it seems a DNS issue. By some reason, the license server cannot be located in the network by its name. I would try to enter the IP address of the server, instead searching it automatically.