Upgraded to Ver 10.1.4 (28883) - Total Loss of Displays

Installed PD 10 in mid-Dec 2014. Yesterday, I Installed the most recent upgrade reminder I'd been receiving periodically. Because I have a new Mac mini from Nov 2014, I didn't think the display issues which a previously offered and uninstalled update included were relevant, but to stop the regular reminders of the available updates I decided to install it.
And that's when the problems started.
After the upgrade I tried to restart my computer, but to no avail. I use two screens, one in the HDMI port and the other in Thunderbolt 2. Both screens would remain dark, one one completely off and the other extremely dim (no images at all, just blank). No wireless keyboard, no trackpad access. I tried using a USB Apple keyboard, nothing.
The only way I got the screens to function (and the Mac to reboot, apparently) was to disconnect the Thunderbolt 2 devices from the Mac Mini. The HDMI screen came back. I reconnected the Thunderbolt devices and once again had two displays and a HD. I hoped that the cause was just a bug related to the reset required by the Parallels upgrade but when I did another Mac restart, still no displays. After disconnecting the Thunderbolt 2 display, nothing seemed to happen until I also disconnected the Thunderbolt HD (each device plugged into its own port).
Once I got the HDMI display back, I went through the reconnection steps again.

Does anyone have a solution for my issues? Everything was OK prior to the upgrade.
If necessary, can I uninstall Parallel Desktop 10.1.4 (28883) and reinstall the prior version I was using? Can I still access a downloadable copy of the pre-28883 version? If so, will I also have to reinstall the Windows 7 and MSFT Office Pro Plus 2010 I currently use?

Please understand that the resolution of this issue is critical and that a response is important to me.

Thank you for your help.

 

Hi PhilippeS1,
This might happen if there any issues with Parallels Tools.
Please uninstall Parallels Tools completely and re-install it again as suggested at : http://kb.parallels.com/4841 and check the display of your Virtual Machine.