This document details how to fix the common issue where a Parallels Virtual Machine is stuck on a black screen.
When a Parallels Virtual Machine is left unattended for a long period of time, it is common for it to get stuck on a black screen, where closing the application, restarting, and reopening will not fix the issue. When Parallels opens back up it only gives the option to resume the machine that is "Suspended" but not actually shut down. To fix this issue, do the following:
At this point you should be able to start up the Virtual Machine again like normal. It is common however for the Virtual Machine to then have an issue shutting down, where it continuously restarts. If you run into this issue, follow the instructions HERE.