The matter is getting more and more misterious... I've always run AH at the same Windows resolution (1024x768), but when I read your post, Tabasco, I tried to lower Windows res and the Film viewer showed the movie in a wider area into the viewing window than before( but not yet in the whole window, neither in 640x480). So, maybe resolution has something to do with my problem, but in a way that I can't figure out: is there a way to change Film Viewer res? Who knows!!!(in fact, it should be the same of the game!) Perhaps this other detail may help to find a reason to this weird behaviour of the FV: when I start the program, in the viewing window there's a sort of "static discharge", as in TV when it can't catch network signal; then the image of the tower appears, as described in my first post.
Anyway, thanks for your help Tabasco. If you have (or anyone else has) some other ideas, please let me know.
P.S. To specify my first post, my Motherboard is a Gigabyte GA-6VX7-1394 and the videocard is shown by Windows as ATI Rage Fury Pro/Xpert 2000 Pro