I found the problem.

I ran an xhtml validator and it found an error with the $10 FLAT RATE SHIPPING header sales text line that I had in includes/languages/english/ocean_front/header.php. Something wrong with the xhtml tags I was using, I guess.

I removed it and the logo appears perfectly in IE and Firefox.

I'll put the $10 FLAT RATE SHIPPING line back in after I figure out the correct xhtml tags.

Thank you so much for your help, Clyde.