Problems with F12 Rendering 2.90.1

Has any one experienced this.

I have my rendering preferences set to render in a new window.
Since updating to Blender 2.90.1, when I hit F12, the render window will pop up like it is getting ready to start the calculations. But nothing happens, no calculations and yet my CPUs all jump to 100% immediately. It will do this no matter if it is sett to GPU, CPU or Hybrid. I have to kill the program and restart Blender. I have not been able to pin down why this is happening. Never happened until 2.90.1

It only does this sometimes. but it does it a lot.

Windows 10 Pro Workstation
Threadripper 3990x
Titan RTX
128 GB Ram

So far, zero problems using 2.83.7.