Hi @Glen_Bannon welcome to Zwift forums.
The timing of your symptoms coincides with our rollout of the Video Screenshots feature for Windows. I’d go into the Settings menu of the game app, and see if the toggle for Video Screenshots is enabled and if so, turn it off. Your machine may not be handling it well.
Also worth asking: are you using the N edition of Windows 11? If yes, there’s a how-to at the bottom of the linked page for what to do.