Please specify what you want, Claude, as it's not very clear what you mean: the tooltips shown on mouseover?
Well, on second read it seems like you mean the header h1 tag, right?
Try to increase the header and header h1 width to 99%, NOT -99%,
as it's an image replacement technique for the h1 tag, try this:
#header{
width:99%;
height:270px;margin:0 auto;background:transparent;}
#header h1,#header h1 a{display:block;height:110px;
width:99%;
text-indent:-9000px;margin:0; padding:0;}
The bolded sections are changed.