Hi Chuckles,
Sorry to hear that. Not fun.
Have you tried to uncheck All frames? Or run it for a Standard render test to gain more information about the causes?
All_frames.jpg
Besides that, no, I have not experienced that, and it sounds to me more like a case for Tech Support.
https://www.maxon.net/en/support-center
Fingers crossed, there is a fix for you available.
All the best