OK Jimmy, I got an idea, I noticed, that you have used 2 seperate images for the header, with gap between them. If you use photoshop, printscreen that image, and crop it down to the required size, do this to the full header, and for every ad. Slice it up. Then lets say you slice it up into 3 images, rotate the ad slice. It will ahve 0 gaps, and should sisplay the same in all browsers. If you dont know what the hell I am on about

Then e-mail me the PSD, and I'll show you what I mean