cubase vst 4.0 is from 1998 my friend
to properly use that software package you will need a 32bit operating system
cubase vst 4.0 was released before windows XP was even invented
you need a pentium II/III or 4 or Intel Core 2 system with 512MB ram only running Win98se
bottom line; your computer is wrong for this software;
its not a good match; you either need different hardware or different software
i would suggest you sell your cubase to a vintage computer enthusiast
and buy a Cubase version that is version 6 / 7 / 8 / 9 somewhere in that range
to be able to use the computer you have
if u are really stuck i would say try running windows 7-32bit and it MIGHT work for you
you might get lucky there; but its 20 year old software