Why are several users unable to log on to Smart View?

Summary:

Two users can only logon to SV a small percentage of time. Security does not seem to be the issue.

Content (required):

Two FCC users from Belgium are most of the time unable to log on to Smart View. The logon screen keeps reappearing, no matter what and how they are trying to log on. One of them is able to log on a different machine and our test user also did not work for them, whereas it works for me. So security does not seem to be the issue, also because they are able to log on to the web browser. It concerns the latest version of SV. They have 32 bit laptops.