Damn Surfn...that's an odd one
Hmmm...you say you do see dozens of other domains in your host file? Don't think you should...the sample Evil posted earlier should be all you see in there. Perhaps your host file has been screwed with and that's the root of the problem. You may indeed have picked up a bug of some sort
Having recently clensed someone else's computer a few times...some of these little nasties are only noticable at certain times...doing certain things. Might explain this kind of odd behavior on your system.