Here is a workaround to updating your Hypervisor setting if you cannot make the change in the configuration - due to being unable to resume the VM.
- Locate your VM file for this virtual machine.
- Right click on the VM file and select "Show Contents".
- Locate the file (which should be at or near the top) that is called "config.pvs"
- Open this file with TextEdit.
- Select the ENTIRE file and copy it.
- Open another text file on your desktop and paste the copied contents into this new file. Name it whatever you like, and save it. This is your backup in case there is a catastrophic problem.
- In the "config.pvs" file, locate this line:
<HypervisorType>0</HypervisorType>
- Change the "0" to "1".
- Save the file
- Now retry starting your VM.
This was what Parallels Support just did for me, and it works now.
Hope this is helpful.