Company Closing Automatically after Login

Hi,

I'm currently trying to restore the NAV 4.0 SP2 company that my customer is using to my test environment.
But when I restore the fbk file, and try to open the company NAV classic NAV automatically closes without giving me an error message.

Does anyone know why NAV closes without telling me any reasons?
When I ran the Debugger while opening the company, I didn't find any issue in the coding.

Maybe it's something to do with the codes that are called, when logging into the company, but I"m not sure, so I'd greatly appreciate if you can let me know of such information as well.

Thank you.

Kenji