I’m trying to build a website and am running across a weird problem. I’m sure a more advanced designer could spot what is going on pretty easily though.
Your site layout is done all with tables, which is kinda not very good. Try delving into using CSS and more semantic elements for layout. Tables should be reserved for tabular data. Also, this image should be set as the background of your header using CSS rather than inline, since it’s not part of each page’s actual content. It’s a presentational element that just makes the site look nicer.
Overall, the graphic design is clean. Just work a bit on the HTML part!
As Rob said you should definitely go with HTML5 and CSS. Tables are forgotten in world of web design. Also use images only when you need too. In this case this black can be done through CSS background color option with little logo image positioned as you wish. With this you will lose that grey line.