Xhtml and ie 6.0

begin
sorry for my english..

ok. I've made my website in XHTML usung css ( layers). Why it doesn't work in IE 6.0 ? But it works very good in Netscape, Opera, even MS IE 5.1 !!!!!!!!! How it's possible ?
I've checked my site witch w3c validator. Everything's ok.

I've made for IE 6.0 another website in HTML construction. It' work's, but only with HTML.

Please help me if you can...