I think I may be having the same or a similar problem.
I want my blog title superimposed on my header image, but I don't want a tagline or logo (they're both incorporated into the image).
There should be a coloured bar (#FFFFCC) 3 px in height between the image and the catagories. The list of header items is:
%pages %bar1 %image %bar1 %cats %bar1
"Show Blog Tagline?" is set at NO, and "Style the blog tagline" is empty. but the tagline appears anyway. (See image: "Tagline where it shouldn't be")
I can removed it by erasing the tagline at General Settings, but then there seems to be a 2 or 3 pixel gap between the base of the header image and bar above the category strip. (See image: "Bar of background colour") It's difficult to see because it's so light, but the width is clearly greater than 3px.
If I remove the bar between the header and the catagory strip, all the catagories are pushed to the right. (See image: "When bar removed, catagories shift right")
I just checked and this is a problem in current editions of Opera, Chrome and Firefox but NOT in IE 7.
My homepage is http://www.thesupercargo.com
Any suggestions gratefully received!