now, I had a similar issue when accessing wal-mart.com, yellowpages.com, newsweek.com, would default to mobile view.
Turns out some Creative software updater decided to put itself into my IE8 user agent, which effed up wal-mart.com.
something else (can't remember what) borked up yellowpages.com and newsweek.com.
Oh it turns out that it remembered i chose to use the mobile version from my ipod a while ago, and i guees it decided thats what i like. once i changed it back it stayed that way.
strange it would attach my preference to my user name and not a cookie.