The code on the page is partly responsible for your problems. For example, it looks like the page was built in about 1995 and never updated - meaning that the code is grossly archaic, however it is still rendered by browsers, so who cares. But the problem is that DW is not rendering with circa 1995 logic, and when it encounters things like this -
<table width="800" border="2" align="center" cellpadding="10" bgcolor="996633" bordercolor="#663333">
it doesn't cut that code a break and supply the missing octothorpe for the deprecated 'bgcolor' attribute value. So, what you saw when the page got darker was the disappearing background color on that table.
But - this is what happens when you try to maintain very old code in a very new authoring system....
