I have javascript switched on in Opera, but Opera's rather picky about what javascript does and doesn't work in it. Come to think of it, the ads seemed to disappear about the time I upgraded Opera from 7.2x to 7.54. I also futzed with my cookie and security settings in Opera and set a few entries in my hosts file to the loopback address about that time, so it might be any of those things.
Not sure about IE, since I seldom use it for anything except Windows Updates. Though I think I tweaked the security pretty high in IE, since Juno uses IE to render HTML e-mail, and if I did, that probably killed javascript over there.