Hello,charles kuchar
Thank you for posting in the Microsoft community.
I understand that the slide show function in your lock screen interface is not working properly.
I see that your problem occurred within a few weeks. I would like to know whether any changes such as system updates, deletion or addition of specific process applications, BIOS updates, etc. were performed before the problem occurred?
Slide show is a relatively basic function. If this abnormal situation that cannot be changed occurs after any system update, you can let us know. At the same time, it is recommended that you put the pictures to be shown in a public path (such as Photos), and the resolution of the pictures should be the same as your display resolution, and then wait a few minutes after clicking Change Slide Show. Sometimes it may start slowly.
If you still cannot work under the premise of the above steps, I would like to ask you to create a new account to test whether the problem is caused by a system problem or an abnormal account configuration file. Follow the steps in the link below to create a new account:
Manage user accounts in Windows - Microsoft Support
This will help us understand if there is a problem with your account profile. If you can use the slide show function correctly on the new account, it means that there may be a problem with your old account. The easiest way is to back up your data files to the new account. You can open "File Explorer -> C Drive -> Old Account Path" in the old account, then copy and paste the required files to the new account and continue to use it normally.
After you refer to the above steps, you can share some information in this thread and I will answer your questions further. Thank you for your understanding and cooperation!
Best Regards,
Rota|Microsoft Community Support Specialist