your friend better update to mozilla, their pop-up blocker is fine-grained and well trained :) 101 things that the Mozilla browser can do that IE cannot was compiled against moz 1.2. now we have moz 1.4 and it's even more stabler :)
as a side note: woody debian user (like me) can add this to their /etc/apt/sources.list:
# newest moz backport to woody
deb http://debian.relativ.org/ ./