If you're having 00-00-0000 date value stored, (Which is special zero value
]; or you can say DateTime's NULL value), then you should know that .NET framework's DateTime object has a limitation over the DateTime value too, this might be the reason for your errors. No matter whether you convert the data to a proper format while extracting the values from MySQL, you still have to make sure that data is valid according to .NET framework's validation rules.
MSDN has resources
Quote:The DateTime value type represents dates and times with values ranging from 00:00:00 (midnight), January 1, 0001 Anno Domini (Common Era) through 11:59:59 P.M., December 31, 9999 A.D. (C.E.) in the Gregorian calendar.
] for that.