No, don't think so -- I don't play with anything along those lines. I'm thinking it's much more likely related to Netscape 4.73. (I did say "ancient". You thought I was kidding. Popup blocker? I settle for avoiding sites with popups when I'm on this machine.) ) I do have a Firefox on here, & don't see it with that, FWIW.
Go to Preferences under Edit. Under the Navigator tab is an option called Smart Browsing. Make sure "Automatically complete..." is checked. Then click advanced, that brings up preferences. Make sure the first three boxes are checked.