When confronted with similar situations of being locked out of a MBP, I ssh login from another computer over the network. Once logged in I then execute the Terminal command: "sudo reboot", which restarts the MBP. This is generally better than just doing a "hard restart" by holding down the power button for 10 seconds since the reboot procedure properly closes down the computer and any applications that are running before restarting.
P.S. Once you are ssh logged into the unresponsive MBP, you can also run "ps auxww" or "top -o cpu" to see if there is some process that is fully utilizing your CPU. And if you feel the need, you can also kill the Windows Server to potentially regain access to the unresponsive MBP without rebooting it.
Any chance you created a separate admin account when you set up your computer? If not, you may want to consider doing so once you figure out your problem. Can you boot into utilities using CMD-R right after you power on? If so, use the terminal to log into root (you did set up a root account, yes?) and change the password of the account you cannot log into using the resetpassword command. Reboot and you should be good to go.