I have 6.0.28000....
I get it to. When you mouseover the panorama.jpg it flashes white for a second. It doesn't do it just once either, it happens every time the mouse is over it.
I'm also using my work machine, which is Windows 2000, but the resources are good enough that it shouldn't be speed, memory or connection related.
I scanned the source and from my meager understanding, didn't see anything that might account for it. The header on the old site never gave me this type of affect though.
Of interesting note, if you move the cursor off the banner while it's flashing, the message that appears in the status bar at the bottom says:
Downloading picture
http://www.slothmud.org/themes/Andergas ... norama.jpg
Again, not sure why a mouseover would cause a complete refresh of that window... but that appears to be exactly what it does.