IT's official, this error is about the stupidist error in the world. It shows up when it wants, there's no reason or logic behind it why it worked a minute ago and not now, and I'm just about to give up. All input comes from an AJAX Calendar extender (see below)...
The code passes values into a stored proc. The stored proc works just fine. 
USE [DB] GO DECLARE @return_value int EXEC @return_value = [dbo].[SP_PUNCH_IN] @EMPLOYEE = N'KK001', @CDATE = N'2013-07-14 12:00:59:999', @TIMEIN = N'2013-07-14 12:00:59:999' SELECT 'Return Value' = @return_value GO To accomodate the date in SQL, I used C# code:
protected void submitPunchIn_Click(object sender, EventArgs e) { SqlConnection connection = new SqlConnection("Data Source=SERVER\\INSTANCE;Initial Catalog=DB;Persist Security Info=True;User ID=username;Password=password"); string sql = "SP_PUNCH_IN"; ...

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