Adobe’s own DW CS5 3-col., HTML5 template fails Windows IE6, IE7 & IE8 in BrowserLab when <header> placeholder text is replaced with 960px x 198px .jpg. (Template width = 960px)
NO OTHER CHANGES were made to the Adobe template or its CSS file other than removing the inline background and display properties per the Adobe text/comments.
Above: IE6 screenshot.
Above: IE7 & IE8 screenshots were identical.
I tested this Adobe template because BrowserLab also failed to display my own files correctly for the same (3) Windows browsers.
Intel Mac Pro 8-core, 8Gb RAM, OS 10.6.8.
The first suggestion is to increase the delay in the BrowserLab Application running in the Browser and refresh. If that doesn't solve the problem please provide the URL (if this site is publically available) or the code snippet showing how the png file is being linked into page.
Thanks - Mike