BOAC,
Not your fault, and I really, really had to try very hard to get it to happen. Allow pop-ups, permit Active-X controls etc.
Default settings on most browsers would protect you, and with AdBlock / NoScript etc. you wouldn't ever even see that the pop-up is being blocked.
Perhaps a timely reminder to ensure that your defences are up to the mark - AV is kept up-to-date, that sensible precautions are adopted when connected to the internet - firewall(s) in place, Adblockers, pop-up blockers and java / scripting / activeX controls set to a secure level. Also consider running as a non-admin account to prevent anything that does get through the net from being able to do any damage.
SD