I've tried the following solutions, but none of them has worked:
1. Opening and closing Studio/restarting my laptop.
2. Renaming the Project Templates to Project Templates_old. Studio has since created a new Project Templates that appears right above the old one.
3. Deleting the file called 'projects.xml' from the C:\Users\[User Name]\Documents\Studio 2019\Projects folder.
I cannot use the antivirus solution that appears here gateway.sdl.com/.../communityknowledge (suggested by Paul in one of the threads), because I cannot even get to the Create a New Project window. The error message appears right after I click on New Project.
In one of the threads, Alison has also suggested trying a Windows repair of Studio, but I'm not sure how to do this.
Is there anything else I could try? The instance of Studio I'm having this issue with has been installed in a brand new Lenovo Yoga 730. I didn't have Studio 2017 installed in this device previously, I installed Studio 2019 from scratch.
Thanks again for trying to help me with this.