Hmmm... I don't believe it's XP, partly because I don't know what XP might
do to manage secure connections beyond what IE caters for, but also because
you say Netscape said connection refused... that implies that either the
site you are going to didn't like your browser's attempts at operating
secure HTTP (and for both IE AND Netscape to have that problem, that's just
too much of a coincidence), or... your ISP is blocking them for some reason!
Were you ever able to access such pages? When did it stop working? Any
recent updates to any software (including XP) in that timeframe? Do you have
a firewall running (other than XP's own) that wasn't running before that
time, or has been updated since?