Forward slash in character string

You either want to look at SET DATEFORMAT (http://msdn.microsoft.com/en-us/library/ms189491.aspx) or a Split-function.

The later is best implemented using a Tally table (like so many other tasks). Jeff Moden has a great article about usage of a Tally table: http://www.sqlservercentral.com/articles/T-SQL/62867/. Even if you decide to solve your particlular problem using SET DATEFORMAT, you should still read Jeff Modens article.

I think its a data issue rather than a TSQL issue. Run this code and then use it to check if all rows are/are not valid as dates in your table:

USE [AdventureWorks]
GO
CREATE TABLE TestDates ( ADate NCHAR(20) ) -- create test table

-- create some test values
INSERT  INTO TestDates
VALUES  ( '01/01/2011' ),
        ( '01/12/2011' ),
        ( '01/22/2011' ),
        ( '01/21/2011' ),
        ( '01/16/2011' ),
        ( '01/30/2011' ),
        ( '21/01/2011' )

-- convert all values that can be converted to dates
SELECT  [dbo].[TestDates].[ADate] ,
        CASE WHEN ISDATE(adate) = 1 THEN CONVERT(DATETIME, adate)
             ELSE ''--adate + 'isnt a date' 
        END AS As_A_Date
FROM    testdates

-- list all values and whether they are or are not convertable
SELECT  [dbo].[TestDates].[ADate] ,
        CASE WHEN ISDATE(adate) = 1 THEN  adate + ' - is a valid date'
             ELSE adate + '- isnt a valid date' 
        END AS As_A_Date
FROM    testdates

-- remove test table
DROP TABLE [dbo].[TestDates]