Grazie Kevin, ci provo :)
Secondo te, posso provarci anche se al momento CFAST non è installato sul computer o se, anche se installato, è come se CFAST si fosse "corrotto" e non si apre più del tutto?

Can you still run CEDIT (the graphical user interface), or is that not working either?

If you can run CEDIT, and the issue is you just cannot run or load your input file, then possibly some issue with the file. If you can run CEDIT, copy the simple.in input from the CFAST install folder (C:\Program Files\firemodels\cfast7\Examples) to non-system folder and see if you can open and run that file using CEDIT. If that works, then the issue is probably the input you made.

Grazie Jason per il tuo suggerimento :)
Purtroppo, da quando mi è comparsa la schermata di errore che vi ho fatto vedere, CFAST/CEDIT proprio non si apre più e neppure permette di re-installarsi in modo da funzionare.
Il file .in sul quale stavo lavorando era salvato direttamente sul desktop del computer aziendale, quindi non era già in una cartella di sistema.
Se vi venissero altre idee per risolvere il problema, ve ne sarei molto grata.

Did you uninstall CFAST or is the prior install still there? If it is still there, open a command window and type cfast. Do you see this:

CFAST

Release Version : CFAST 7.7.3
Revision : CFAST7.7.3-4-g0c33733b
Revision Date : Thu May 12 10:19:24 2022 -0400
Compilation Date : Fri 05/13/2022 01:48 PM

Normal exit from CFAST

If this works, open your file with a text editor like notepad. Does it look like a text file or do you see some text and some garbage. If you see garbage then something went wrong writing the file, If it looks like a normal text file, then change directories in your command window to where the file is and type (jobname is whatever your file name is):

cfast jobname.in

Does it run or do you see error messages?

If it runs, then you would have the option of making your CFAST input by hand. It is just a text file. Not as convenient as the GUI.

Another option if you didn't unistall is open the control panel, go to remove programs, and uninstall cfast. That might let you reinstall.

Ci provo, grazie, e ti faccio sapere :)