I know someone who keeps getting a pop-up error message on their computer. It started happening not long after trying to download an internet program. The message says that there is an error on the page, usually after any new webpage loads. If you try to type, that message keeps popping up, again and again. I don't know if it has something to do with the html, or not. She did a full anti-virus scan, but found nothing. Also, she cleaned her hard drive, and then defragged. The message still comes up.

Anyone have any ideas?