I just downloaded the IE8 full release so I could test a site I just created. [Example Deleted]
Focus on the left sidebar background image. It is suppose to be a 1x1 se
It may be a rendering error in IE8, or perhaps it's some function to smooth the edges of repeated images that gives you an unexpected result. Either way it's not very surprising that you get problems using such a small image. Do you realize that the browser has to draw the image 190152 times to render the page?
I am using a 10x10 semi transparent png as background for a div in a page, and it renders just fine in IE8.