I would like to see the code that's giving you trouble, but "1/15/2010 8:46:01 AM" is a valid date in en-US encoding. Make sure you are using the en-US culture; don't assume it based on the machine you are using for development/test. Also, if DateTime strings are based on input, consider the cases where the user can override the current culture via the Control Panel.
Here's an example from MSDN:
string dateString;
CultureInfo culture;
DateTimeStyles styles;
DateTime dateResult;
// Parse a date and time with no styles.
dateString = "03/01/2009 10:00 AM";
culture = CultureInfo.CreateSpecificCulture("en-US");
styles = DateTimeStyles.None;
if (DateTime.TryParse(dateString, culture, styles, out dateResult))
Console.WriteLine("{0} converted to {1} {2}.",
dateString, dateResult, dateResult.Kind);
else
Console.WriteLine("Unable to convert {0} to a date and time.",
dateString);