The same thing happened to me. Under Tools, select Password Manager, Manage Stored Passwords. In the resulting popup, scroll down and you should see your five entries for the ChipBoard. Delete these. The next time you access the board, or maybe it's just the next time you post something, a popup will appear asking if you want to save your password. Check off No, or Never For This Site (can't remember exactly what it says, but you get the idea).

As for the other suggestions, I've heard nice things about Mozilla, but Netscape works so well I've never had the need to try it. As far as IE, I don't like using it at all. Seems dated compared to Netscape, and I don't need to voice my opinion of Microsoft here.

Hope this helps
Steve