function check_user(f) 
	{

		f.value=filterNum(f.value);

    		function filterNum(str) 
    		{
          		re = /\$|,|@|#|~|`|\%|\*|\^|\&|\(|\)|\+|\=|\[|\]|\[|\}|\{|\;|\:|\'|\"|\<|\>|\?|\||\\|\!|\$/g;
                  	return str.replace(re, "");
     		}
     			
     			

	}
	function alert_require(field,alerttxt)
	{
		with (field)
		{			
			if (value==null||value=="")
  			{
  				alert(alerttxt);
  				return false;
  			}else{
  				return true;
  			}
		}
	}
	function check_form(thisform)
	{
		with (thisform)
		{
			if (alert_require(username,"Please enter your username to login.")==false || alert_require(password,"Please enter your password to login.")==false)
  			{
  				return false;
  			}
  		}
  				
  				
	}