I have a catalog-type website, view only with passwords.  For 98% of the people it works find, including myself.
However there are a few on a steady basis, new people that I give passwords to, who cannot see the webpage.  One said the page says "not viewable".  I recheck their passwords and recheck the website and everything is fine with my browser.  I work on an imac, and i'm a beginner. What could cause this and how do I fix it?