function CheckFile(){
	var file = arguments[0];
	var ajax = new Ajax.Request('download.php',
		{
				method:'get',
				parameters: {task: 'check', file: file},
				onSuccess: function(transport){
					try{
						var json = transport.responseText.evalJSON();
						if(true == json.success) {
							document.location = 'download.php?task=get&file=' + file;
						}else{
							$('error-message').show();
							setTimeout(function(){
									$('error-message').hide();
								}, 15000);
						}
					}catch(e){}
				},
				onFailure: function(){ 
					$('error-message').show();
							setTimeout(function(){
									$('error-message').hide();
								}, 15000);
				}
		}
	); 
}