This has been driving me crazy - in how do you format the CSS to make IE6 stop glitching up dashed/dotted lines? Check my site below; when a user scrolls the lines turn semi-solid.
Since I don't see any dotted or dashed lines on your page in any browser, that's hard for me to say - though those types of rendering errors are usually caused by elements not tripping 'haslayout' or one of the oddball comment/float combination quirks (though that's more likely to cause dissapearing content and/or double rendering)
Welcome Bar? do you have to log in to see that or something? Only dotted lines I'm seeing are on your hover states for anchors - and those are working fine everywhere. Oh, wait... I see it. Ok, I don't see it, but I see where you mean. Had to zoom in 5x since in Opera and FF the 'dotted' grey on a grey background just looks like a solid line... Now that I see what you mean in IE6... Hmm. I'd assume that's a haslayout issue - has most of the telltales. I'd make sure haslayout is tripped on both the element wrapping that section, and the section itself. Though there are other code 'issues' like the unneccesary clearing div, paragraphs around non-paragraph content, two or three times as many DIV and classes as needed, presentational markup, etc, etc. In addition to making certain 'haslayout' is tripped on that section, I'd set the outermost container to wrap floats to lose the clearing div, etc, etc...
That's not his problem though - when you scroll up and down using the scrollbar the border is not being rendered correctly. It's the traditional IE not erasing old content on scroll bug - I'm just suprised to see it just on a border and not on the whole element.