Visitor Log bug (5 replies)

Everything was OK for many years and now if I want to view detailed visitor log then I get an error.
I understand the problem was already solved by someone here.
Please, can anybody here to give me a solution for this issue?

Here is a print screen attached here and this is the code error:

WARN Live[2014-05-16 12:28:13] [60a26] Failed to get data from API: Trying to add two strings values in DataTable\Row::sumRowArray: 'Kê™T?{r®' + 'Áêù?“v¥Z'#0 /nfs/c10/h01/mnt/143258/domains/domain.com/html/piwik/core/DataTable/Row.php(501): Piwik\DataTable\Row->sumRowArray('K??T?{r?', '?????v?Z')#1 /nfs/c10/h01/mnt/143258/domains/domain.com/html/piwik/core/DataTable/Row.php(469): Piwik\DataTable\Row->getColumnValuesMerged('sum', 'K??T?{r?', '?????v?Z')#2 /nfs/c10/h01/mnt/143258/domains/domain.com/html/piwik/core/DataTable/Filter/Truncate.php(105): Piwik\DataTable\Row->sumRow(Object(Piwik\DataTable\Row), false, false)#3 /nfs/c10/h01/mnt/143258/domains/domain.com/html/piwik/core/DataTable/Filter/Truncate.php(72): Piwik\DataTable\Filter\Truncate->addSummaryRow(Object(Piwik\DataTable))#4 /nfs/c10/h01/mnt/143258/domains/domain.com/html/piwik/core/DataTable.php(426): Piwik\DataTable\Filter\Truncate->filter(Object(Piwik\DataTable))#5 /nfs/c10/h01/mnt/143258/domains/domain.com/html/piwik/core/API/DataTableGenericFilter.php(143): Piwik\DataTable->filter('Truncate', Array)#6 /nfs/c10/h01/mnt/143258/domains/domain.com/html/piwik/core/API/DataTableGenericFilter.php(37): Piwik\API\DataTableGenericFilter->applyGenericFilters(Object(Piwik\DataTable))#7 /nfs/c10/h01/mnt/143258/domains/domain.com/html/piwik/core/Plugin/Visualization.php(561): Piwik\API\DataTableGenericFilter->filter(Object(Piwik\DataTable))#8 /nfs/c10/h01/mnt/143258/domains/domain.com/html/piwik/core/Plugin/Visualization.php(314): Piwik\Plugin\Visualization->applyGenericFilters()#9 /nfs/c10/h01/mnt/143258/domains/domain.com/html/piwik/core/Plugin/Visualization.php(171): Piwik\Plugin\Visualization->applyFilters()#10 /nfs/c10/h01/mnt/143258/domains/domain.com/html/piwik/core/Plugin/ViewDataTable.php(375): Piwik\Plugin\Visualization->buildView()#11 /nfs/c10/h01/mnt/143258/domains/domain.com/html/piwik/core/Plugin/Controller.php(281): Piwik\Plugin\ViewDataTable->render()#12 /nfs/c10/h01/mnt/143258/domains/domain.com/html/piwik/plugins/Live/Controller.php(93): Piwik\Plugin\Controller->renderReport('getLastVisitsDe...')#13 /nfs/c10/h01/mnt/143258/domains/domain.com/html/piwik/plugins/Live/Controller.php(101): Piwik\Plugins\Live\Controller->getLastVisitsDetails()#14 [internal function]: Piwik\Plugins\Live\Controller->getVisitorLog()#15 /nfs/c10/h01/mnt/143258/domains/domain.com/html/piwik/core/FrontController.php(500): call_user_func_array(Array, Array)#16 /nfs/c10/h01/mnt/143258/domains/domain.com/html/piwik/core/FrontController.php(85): Piwik\FrontController->doDispatch(NULL, NULL, NULL)#17 /nfs/c10/h01/mnt/143258/domains/domain.com/html/piwik/core/dispatch.php(34): Piwik\FrontController->dispatch()#18 /nfs/c10/h01/mnt/143258/domains/domain.com/html/piwik/index.php(47): require_once('/nfs/c10/h01/mn...')#19 {main}