Go to Excel Options > Save > Save Files in this format > Select "Excel Workbook(*.xlsx)". This problem occurs if you are using an older version of excel file (.xls) instead of .xlsx. The older version does not allow more than 65k rows in the excel sheet.
Once you have saved as .xslx, try executing your code again.
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Looking more into your problem, it seems that the problem might be locale specific. Does the code work on another machine? What value does the cell have? Is it datetime format? Have a look here:
http://support.microsoft.com/kb/320369
http://blogs.msdn.com/b/eric_carter/archive/2005/06/15/429515.aspx