blurry header image in IE7 and IE8

On this test page: http:// www.onebagoneearth.com/ Products-test , where it says "oboe love series", "oboe kind series", etc, when you hover over that text (which is a background-image) in IE7 and IE8(at least on Vista, and also with IETester), the image blurs (not just by being opaque though...that would be the normal hover effect). Why is that?

The same thing doesn't happen on this page with similar CSS: http:// www.开发者_StackOverflow中文版onebagoneearth.com /Products . If it's the zoom:1 bit of CSS, I don't understand why it would do that on one page and not the other.

I see what you mean, but on my computer it doesn't blur, it gets a noisy outline of dark gray pixels instead.

It's because you are using a PNG image with an alpha channel, and are applying a filter to it. Internet Explorer doesn't handle this correctly and draws the semi transparent pixels against a solid background instead of the actual background.

When this happens and how it appears exactly may vary from computer to computer, and even on the same computer in different situations. That's why some people experience it and some don't.