I now have PrintShop 23.1 up and running on my Windows 8.1. This is what worked for me:
1. First, RIGHT CLICK on the Printshop icon on your desktop, select Properties, click on Compatibility, and make the selection to run the program in Compatibility Mode for Windows 8. Click Apply, then OK to exit.
2. Double click the Printshop icon on your desk top to open Printshop. If it works - great! However, if it does NOT work, it means the .NET framework required to run the program was uninstalled or corrupted by the Windows 8.1 upgrade and needs to be reinstalled, so please do the following.
3. From your Control Panel, select Programs and Features; in Programs and Features, uninstall Printshop. (You get to the Control Panel by clicking on Settings in your desktop popout taskbar, usually on the right side.)
4. Check to make sure the Microsoft .NET framework is also uninstalled. If not, attempt to uninstall. If you have recently gone to Windows 8.1, it may be partly or fully uninstalled because the 8.1 upgrade might have removed (or damaged) part of it. If it will not uninstall, don't worry! Proceed . . .
5. Follow this step even if you see no sign of the .NET framework in Programs and Features. It is almost certain that you have debris from it on your computer because this is a known problem, and Printshop will not reinstall unless the debris is removed. THEREFORE, clean your computer by using the Microsoft .NET Framework Cleanup Tool found at the following link:
.NET Framework Cleanup Tool
6. AFTER Printshop is once again installed, it will very likely NOT RUN unless you follow Step #1, above, to run it in Windows 8 Compatibility Mode.