This is a common problem encountered with HYSYS. The files are not "downward compatible", so you cannot open files from a later version of HYSYS. However, I think that you can save files (in the newer version) as earlier-version files, or as a different file type. You should ask the person who provided you with the file to save it in a format that is appropriate for your version.
Build 1706 seems a very old version to me, by the way - they are now somewhere up from 3800, so it may be impossible to use your version with the case file that the other person gave to you. Regards,
Joerd