background-image position in IE6 with png images doesn't work!

After spending about three hours hacking CSS and searching the web today I've discovered that IE6 doesn't respect the positioning of your background-image if you are using png's. Both gif and jpg images work as expected.

So if you're wondering why something like this:

background: White url(../Images/promobox_bottom.png) no-repeat center bottom;

isn't rendering correctly in IE6, try a different image type.