Downloading software opens different program

I am not sure if I should post this here or on Win XP, but here goes. I have been trying to install a package Psiwin 2.3.3 for my Psion 3mx (by now a very old device, but still works well). The software enables me to transfer files to and from my Psion. The download seems fine, but when I try to install it opens an installation for Fujifilm Twain Driver rather than the Psiwin program! I have tried the download from a number of sources with the same result. It does not happen with any other download or any other software. I have been on a Psion forum and found one other person with the same problem, but no one seems to have responded.

Can anyone advise me?

Thanks

Gareth