By default, the DateTime.Parse() method assumes that dates given to it are in US format. In order to get it to process a non-US format date, such as the UK dd/mm/yyyy format, we need to pass it the appropriate "culture" information, like so:
C#
// we need to have imported System.Globalization
// using System.Globalization;
// fetch the en-GB culture
CultureInfo ukCulture = new CultureInfo("en-GB");
// pass the DateTimeFormat information to DateTime.Parse
DateTime myDateTime = DateTime.Parse("18/09/2004",ukCulture.DateTimeFormat);
VB.NET
' we need to have imported System.Globalization
' Imports System.Globalization
' fetch the en-GB culture
Dim ukCulture As CultureInfo = New CultureInfo("en-GB")
' pass the DateTimeFormat information to DateTime.Parse
Dim myDateTime As DateTime = DateTime.Parse("18/09/2004", ukCulture.DateTimeFormat)
Once converted, you can then call things like myDateTime.ToShortDateString() and actually get the format you expect - nice! :)
In case you're wondering what that en-GB bit is actually about - the first two characters give the ISO Language Code (ISO 639), and the second two give the ISO Country Code (ISO 3166).