Error message while trying to save first segment (SDL Trados Studio 2017)

Hello!

I'm translating a document from German to Italian with version 2017. When I try to save the first segment I get the following error message: Impossibile trovare il file specificato (The specified file could not be found). This is the second time it happens with the same client, but they couldn't help me...

Can anybody help with this?

Thank you.

Barbara