BackGround image not show on IE7 issue

Today I got a background image issue. I used body {background: url(../images/bg.jpg) fixed center no-repeat}   and it worked perfect on FireFox3. While it didn't show anything on IE7. I googled a lot, but no luck to solve my problem.

Someone said it was caused by the image path. IE can't recognize the images which are not in the current directory very well. I moved the image to the css folder and it still didn't work.

One person said he got the issue fixed by adding some css : add{position : relative}  before background. Still not work for me.

God! very very big headache!!! Fucking IE!!!

Finally, I turned to the image set as background. Great! That's the problem. Try to visit www.mysite.com/images/bg.jpg on IE, and it displayed a X, but it showed well on FireFox...

The image must be broken after I resized it... But Why FireFox can read it?!!

Regenerate the image and everything went well. Fucking IE!!!