Regions/Locales and Pulling DateTimes( From Strings) from a Database - vb.net

Question

I've been having several problems lately with clients that are using a different Windows Region setting than I am. I cannot seem to find a way to fix it. The error is as follows:
The type initializer for 'InventoryDataTable' threw an exception. ---> System.TypeInitializationException: The type initializer for 'InventoryDataTable' threw an exception. ---> System.FormatException: String was not recognized as a valid DateTime.
The error occurs when users load the application and their region settings do not match my own. The application loads up a dataset and attempts to receive a small amount of data before allowing the user to log in. When this is removed, the problem occurs immediately after the user logs in to the app.
I cannot seem to find the proper settings to force the user to use either my Region, or to allow the application to figure it out on it's own...
Exact error:
System.InvalidOperationException: An error occurred creating the form. See Exception.InnerException for details. The error is: The type initializer for 'InventoryDataTable' threw an exception. ---> System.TypeInitializationException: The type initializer for 'InventoryDataTable' threw an exception. ---> System.FormatException: String was not recognized as a valid DateTime.
at System.DateTimeParse.Parse(String s, DateTimeFormatInfo dtfi, DateTimeStyles styles)
at System.DateTime.Parse(String s)
at Invasion_3042_v2.INVDataSet.InventoryDataTable..cctor() in C:\Users\Tdata\Desktop\I2.original\Invasion 3042 v2\INVDataSet.Designer.vb:line 7588
--- End of inner exception stack trace ---
at Invasion_3042_v2.INVDataSet.InventoryDataTable..ctor()
at Invasion_3042_v2.INVDataSet.InitClass() in C:\Users\Tdata\Desktop\I2.original\Invasion 3042 v2\INVDataSet.Designer.vb:line 4296
at Invasion_3042_v2.INVDataSet..ctor() in C:\Users\Tdata\Desktop\I2.original\Invasion 3042 v2\INVDataSet.Designer.vb:line 447
at Invasion_3042_v2.INV3042LOGIN.InitializeComponent() in C:\Users\Tdata\Desktop\I2.original\Invasion 3042 v2\INV3042LOGIN.Designer.vb:line 39
at Invasion_3042_v2.INV3042LOGIN..ctor() in C:\Users\Tdata\Desktop\I2.original\Invasion 3042 v2\INV3042LOGIN.vb:line 100
--- End of inner exception stack trace ---
at Invasion_3042_v2.My.MyProject.MyForms.Create__Instance__[T](T Instance) in 17d14f5c-a337-4978-8281-53493378c1071.vb:line 190
at Invasion_3042_v2.My.MyProject.MyForms.get_INV3042LOGIN()
at Invasion_3042_v2.My.MyApplication.OnCreateMainForm() in C:\Users\Tdata\Desktop\I2.original\Invasion 3042 v2\My Project\Application.Designer.vb:line 35
at Microsoft.VisualBasic.ApplicationServices.WindowsFormsApplicationBase.OnRun()
at Microsoft.VisualBasic.ApplicationServices.WindowsFormsApplicationBase.DoApplicationModel()

Answer 1

Posting the actual code causing the issue would have helped, but I can put forth a pretty good guess at what's going on.
Could it be that the date format being stored into your centralized database is always of a given format (maybe US?). If so, what is very likely happening is the following:
A date like 1/14/2012 is returned from a query to your database. The code running on your problem clients are parsing the date using perhaps European date regional settings. (In the EU and most other countries in the world 14-Jan-2012 is expressed as 14/01/2012 aka dd/MM/yyyy, not MM/dd/yyyy.
Try either specifying that you want to always use a known, base regional setting in your config file like this:
<globalization requestEncoding="utf-8" responseEncoding="utf-8" culture="en-US" />
...or parse your dates using a specified culture setting like this to avoid defaulting to the local system setting that does not match your server-side expectations.
DateTime.Parse("1/14/2012", new CultureInfo("en-US")); // or whatever culture your server database expects...