Not sure what it means exactly but it's probably a javascript error. Either the page is broken or it uses features that your browser doesn't support. Just a guess, though.
Hi navigator. If you mean the lines under words here on a2k, that's a feature that I don't know much about, but I believe it has something to do with sponsorship.
I use Firefox, but explorer is usually ok depending on the site you are trying to access. Maybe you could paste the link that caused the error and I could see if I can figure it out.