Hi Benmurphy.
Thanks for reporting this issue in Microsoft Community.
In your description, your computer contains multiple monitors, and when you enter and exit the screen saver, windows and applications on your primary monitor freeze, and can only be temporarily released by Alt + Ctrl + Delete.
This problem can come from several sources, such as the system's power plan, the graphics card's drivers, or the monitor's own power management, etc. We need to know some information and you need to perform some tests to determine what the problem is.
When did this problem occur? Did it start when you were using a second monitor? Or was it present when you were using one monitor?
If conditions allow, please use another monitor as your primary monitor or set the other monitor as your primary monitor to see if the same problem exists.
Also, you can try connecting just one monitor (testing each monitor individually) to see if there is a problem.
You can also set the power plan to High Performance
1 Right-click the Start button and select Power Options
2 In the selected plan, find High performance and select it.
3 If you don't find it, try clicking Hide additional plans, then select High performance
See if you have the same problem after that.
If in any case there is a problem with the primary monitor, then this could be a problem with the graphics card or the drivers for the card.
Please download and install the appropriate display adapter driver for your graphics card, depending on the model or serial number of your card, using the link below
https://www.nvidia.com/en-us/drivers/
Disclaimer: This is a non-Microsoft website. The page appears to be providing accurate and safe information. Watch out for ads on the site that may advertise products frequently classified as PUP (Potentially Unwanted Products). Thoroughly research any product advertised on the site before you decide to download and install it.
See if the same problem exists after installing the new driver. If it still exists, you can try a different version.
In addition, you can also try downloading and pressing the corresponding monitor driver from the official website of the monitor's device manufacturer.
You can also try to set the power management of your Nvidia graphics card by setting it to performance mode through the Nvidia control panel.
Please try the above options and let me know the results, I will determine the problem for you based on your results.
Thank you for your understanding and support.
Best regards,
Zev - MSFT | Microsoft Community Support Specialist