Saving changes is not permitted Error in SQL Server 2008 Express

If you are getting this error-
Saving changes is not permitted. The changes you have made require the following tables to be dropped and re-created. You have either made changes to a table that can't be re-created or enabled the option Prevent saving changes that require the table to be re-created.
 
Tools -> Options -> Designers->Table and Database Designers-> and uncheck the option "Prevent saving changes that require table re-creation.