Fixed columns disappear when scrolling down to the bottom of the rows

Hello, I am trying to accomodate the DataTablesn and the FixedColumns plugins. Ignoring the fact that it is quite slow even on my i7/8GB MBP, everything seems to work, except of one issue:

When I scroll down the rows, almost down, the fixed columns dissapear.

To better understand me, I am adding the links to the two images - the first one shows the look just after the load of the page - and the second shows it after I scroll down...

http://old.betacontrol.cz/data/kk/blazek/2013-01-31_23-23-43.png
http://old.betacontrol.cz/data/kk/blazek/2013-01-31_23-24-23.png

The only way how to re-display the fixed columns is to refresh the page...

The component initialization code looks like this:

$(document).ready(function() {
	startListTable = $('#dataTable1').dataTable( {
		"aoColumns": [
			{"sTitle":"ID","sClass":"left","bSortable": true},
			{"sTitle":"Příjmení","sClass":"left","bSortable": true},
			{"sTitle":"Jméno","sClass":"left","bSortable": true},
			{"sTitle":"Ročník","sClass":"left","bSortable": true},
			{"sTitle":"Klub/Město","sClass":"left","bSortable": true},
			{"sTitle":"Zaplaceno","sClass":"left","bSortable": true},
			{"sTitle":"Registrace","sClass":"left","bSortable": true},
			{"sTitle":"Trať","sClass":"left","bSortable": true},
			{"sTitle":"Název team","sClass":"left","bSortable": true},
			{"sTitle":"O pohár ředitelky ATVS Palestra","sClass":"left","bSortable": true},
			{"sTitle":"Akademické MČR","sClass":"left","bSortable": true},
			{"sTitle":"kola","sClass":"left","bSortable": true},
			{"sTitle":"","sClass":"left","mRender":function(data,type,row){return data;},"bSortable": false},
			{"sTitle":"","sClass":"left","mRender":function(data,type,row){return data;},"bSortable": false}],
		"aaData": startListData,
		//"sPaginationType": "full_numbers",
		//"iDisplayLength": 100,
		//"aLengthMenu": [10, 25, 50, 100, 1000],
		"bScrollInfinite": true,
		"bScrollCollapse": true,
		"sScrollY": "300px",
		"sScrollX": "100%",
		"sScrollXInner": "300%",
		"oLanguage": {
			"sLengthMenu": "Zobrazit _MENU_ záznamů na stránku",
			"sZeroRecords": "Žádné záznamy",
			"sInfo": "Zobrazeno _START_ do _END_ z _TOTAL_ záznamů",
			"sInfoEmpty": "Zobrazeno 0 do 0 z 0 záznamů",
			"sSearch": "Filtr: ",
			"oPaginate": {
				"sFirst": "<<",
				"sPrevious": "<",
				"sNext": ">",
				"sLast": ">>"
			}
		},
		"fnRowCallback": function(nRow) {
			if(nRow.cells[2]) nRow.cells[2].noWrap = true;
			return nRow;
		}        
	} );
	new FixedColumns(startListTable, {
		"iLeftColumns": 4,
		"iLeftWidth": 350
	} );    
} );