PNGs look blurred around the edges in IE7

Hi there,

I have been developing an application with a lot of transparent png buttons and just using illustrator - saveforweb feature to save
png buttons with a transparent background. I think I used png-24, dont think I’ve ever had this problem before so I thought I’d ask someone with more Graphics experience why they appear blurred around the edges in only IE7?

kind regards

Silversurfer