Proteus 8.6 saves files in temp folder

[panoss]

When I create a project in Proteus, I save it in, e.g a folder like: F:\Files\ProteusProjects\Test.
BUT the files of the project, source files like main.c are being saved in a temp folder!
Like: C:\Users\PANAGI~1\AppData\Local\Temp\aea8c683602c4e309857b9e94231c720\PIC16F876A_

And when I reboot, let's say, my pc (or even without rebooting) they get deleted!
Because they 're in the temp folder!

And when I open (or just rebuild) the project in Proteus I get an error like 'file C:\Users\PANAGI~1\AppData\Local\Temp\aea8c683602c4e309857b9e94231c720\PIC16F876A_\main.c' not found!!!
And in the project explorer appears a question mark by the name of the file....
Result is I have lost quite a few projects  .

How can I fix this?