I've searched for the hex color code in the templates and I've also looked though all the colors in the All Style Options and have not been able to find where it is coming from.
This should help - Forum Home Template However, that is for the default style. If you've modified things a lot, you may need to go ask the style designer for help if you can't figure out the classes yourself (I use firebug as an add-on to firefox for things like that).
Thanks Lynne. Apparently it is only doing it in IE 6 (was working on it at work last night and they never update any thing on the computers). There is no blue line in FF or IE8.