File Save As error

After doing the same thing for almost a year, I suddenly cannot save my project files any more. This is the message:

"Could not save project xx

Scrivener does not allow saving to a project’s .scriv folder.

Please select another location."

No matter which location I select, including a blank thumb drive, I get that message. What am I suddenly doing wrong?

I have the same problem on two different computers - both my PC which doesn’t connect to the internet and my laptop which does and to which I have just downloaded a new copy of hte Scrivener software. I want to move a project from the PC to the laptop via a USB and it won’t let me!