What do I do?????
Should I log out? Should I disconnect? Press the X?
Nope, don't need to go through all that. When you come back and see your screen is black, just hit any button to wake it up.
Then hit Control+Alt+Delete and then a screen will pop up asking for a password. Just put in your AD password that you use to log into VMware.
Your VDI will be back up and running, just like it was before you went to lunch.