We are runing PRTG NM on Windows 7 Professional with slovak localization. When trying to show historical data, we get incorect time span for every interval setting and the data are not shown. -> Report Time Span: 30. 12. 1899 0:00:00 - 30. 12. 1899 0:00:00 I have customized regional setting to english, but no effect on date understanding.