Hi,

I have used nice menu to build my drupal menu system.I have a problem that after I selected a menu that menu
will be disappeared.see the screen shots

http://img806.imageshack.us/i/68398038.jpg/
http://img571.imageshack.us/i/36474386.jpg/

here is my css file.

ul.nice-menu,
ul.nice-menu ul {
  list-style: none;
  padding: 0;
  margin: 0;

   
}

ul.nice-menu li {
  border: 1px solid #ccc;
  border-top: 0;
  float: left;
  background-color: #faa435;
  /* Additional overrides to deal with Garland theme. */
  margin: 0;
  padding-left: 36px;
  background-image: none;
   font-family:Trebuchet MS;
    font-size:13px;
	text-decoration:none;
	font-weight:bold;
	padding-top:1px;
	 
}

/* Overrides for Garland header. */
#header-region ul.nice-menu li {
  margin: 0;
  /* Padding rules are needed to deal with Garland's header line-height. */
  padding-top: 0.1em;
  padding-bottom: 0.1em;
  background: #eee;
}

ul.nice-menu a {
  padding: 0.3em 5px 0.3em 5px;
  font-family:Trebuchet MS;
    font-size:14px;
	text-decoration:none;
	color:#FFF;
}



ul.nice-menu ul,
/* Repeat for Garland header. */
#header-region ul.nice-menu ul {
  top: 1.8em;
  left: -1px;
  border: 0;
  border-top: 1px solid #ccc;
  margin-right: 0;
}

/* Override for Garland header. */
#header-region ul.nice-menu ul {
  top: 1.7em;
}

ul.nice-menu ul li { /* sub menu drop down */
 /*width: 12.5em;*/
 padding-left:12px;
 width:150px;
 

 
}

/******************************
 VERTICAL (left/right) menus
******************************/

/* This is the default width of all vertical menus. */
ul.nice-menu-right, ul.nice-menu-left,
ul.nice-menu-right li, ul.nice-menu-left li {
  width: 12.5em;
  
}

/* VERTICAL menus where submenus pop RIGHT (default). */
ul.nice-menu-right ul {
  width: 12.5em;
  left: 12.5em;
  top: -1px;
}

ul.nice-menu-right ul ul {
  width: 12.5em;
  left: 12.5em;
  top: -1px;
}

ul.nice-menu-right li.menuparent,
ul.nice-menu-right li li.menuparent {
  background: #eee url(arrow-right.png) right center no-repeat;
}

ul.nice-menu-right li.menuparent:hover,
ul.nice-menu-right li.over,
ul.nice-menu-right li li.menuparent:hover,
ul.nice-menu-right li li.over {
  background: #ccc url(arrow-right.png) right center no-repeat;
  text-decoration:none;
	color:#FFF;
}

/* VERTICAL menus where submenus pop LEFT. */
ul.nice-menu-left li ul {
  width: 12.5em;
  left: -12.65em;
  top: -1px;
}

ul.nice-menu-left li ul li ul {
  width: 12.5em;
  left: -12.65em;
  top: -1px;
}

ul.nice-menu-left li.menuparent,
ul.nice-menu-left li li.menuparent {
  background: #eee url(arrow-left.png) left center no-repeat;
}

ul.nice-menu-left li.menuparent:hover,
ul.nice-menu-left li.over,
ul.nice-menu-left li li.menuparent:hover,
ul.nice-menu-left li li.over {
  background: #ccc url(arrow-left.png) left center no-repeat;
  text-decoration:none;
	color:#FFF;
}

ul.nice-menu-left a, ul.nice-menu-left ul a {
  padding-left: 14px;
  text-decoration:none;
	color:#FFF;
}

/******************************
 HORIZONTAL (down) menus
******************************/

ul.nice-menu-down {
  float: left;
  border: 0;
 
}

ul.nice-menu-down li {
 /* border-top: 1px solid #ccc;*/
 
}

ul.nice-menu-down li li {
  border-top: 0;
}

ul.nice-menu-down ul {
  left: 0;
}

ul.nice-menu-down ul li { /* sub menu */
  clear: both;
  background-color:#faa435;
  
 
}

ul.nice-menu-down li ul li ul,
/* Repeat for Garland header. */
#header-region ul.nice-menu-down li ul li ul {
  left: 12.5em;
  top: -1px;
}

ul.nice-menu-down .menuparent a {
  padding-right: 15px;
  text-decoration:none;
	color:#FFF;
}

ul.nice-menu-down li.menuparent,
/* Repeat for Garland header. */
#header-region ul.nice-menu-down li.menuparent {
 /* background: #eee url(arrow-down.png) right center no-repeat;*/
}

ul.nice-menu-down li.menuparent:hover,
ul.nice-menu-down li.over,
/* Repeat for Garland header. */
#header-region ul.nice-menu-down li.menuparent:hover,
#header-region ul.nice-menu-down li.over {
 /* background: #ccc url(arrow-down.png) right center no-repeat;*/
 text-decoration:none;
	color:#FFF;
}

ul.nice-menu-down li li.menuparent,
/* Repeat for Garland header. */
#header-region ul.nice-menu-down li li.menuparent {
 /* background: #eee url(arrow-right.png) right center no-repeat;*/
}

ul.nice-menu-down li li.menuparent:hover,
ul.nice-menu-down li li.over,
/* Repeat for Garland header. */
#header-region ul.nice-menu-down li li.menuparent:hover,
#header-region ul.nice-menu-down li li.over {
 /* background: #ccc url(arrow-right.png) right center no-repeat;*/
}


 ul.nice-menu,
  ul.nice-menu ul,
  ul.nice-menu li {
    border: 0;
    background: none;
  }

  ul.nice-menu-right li.menuparent,
  ul.nice-menu-right li li.menuparent{
   /* background: url('arrow-right.png') right center no-repeat;*/
  }

  li.menuparent li, li.menuparent ul {
    background: #eee;
  }
  
 
  

what could be the problem with this?

Thanks