HTML DOCTYPE and elements

#nav {
margin:0;
padding:0 7;
background:#FEFFFF url(tti.png) top left no-repeat;
float:left;
width:1000;
border:2px solid #42432d;
border-width:0px 0;
}

#nav li {
display:inline;
padding:0;
margin:0;
}

#nav a:link,
#nav a:visited {
color:#000;
background:#64E3F7 url(lb.png);
padding:11px 20px 12px 20px;
float:left;
width:auto;
border-right:0px solid #FEFFFF;
border-image:url("lb.png");
text-decoration:none;
font:bold 1em/1em Calibri, Trebuchet MS, sans-serif;
}


#nav li:first-child a {
background:url(l1.png);
border-top-left-radius:25px;
border-bottom-left-radius:25px;

}

#nav a:hover,
#nav a:focus {
background:#BDF4FC url(nva.png);
}


#nav a:active {
background:#004CFF;
color:#fff;
}
</style>

• or menu. It's full background is not displayed. When I remove the DOCTYPE specification, its works perfect. But the problem with removing the DOCTYPE is that if I remove it, some elements of the page wont work in IE. Those elements include a slider and a news scroller. You can have a look at the page and you'll understand everything. The URL:http://mypmail.x10.bz/012/sample/[^]
  
  The radius property of the search button is also not working.
  Any ideas?
  
  Thanks