You made changes to the label that could not be recreated or enabled the "Prevent saving changes that require the table to be recreated" option.

MS SQL Server 2008 When you are finished building a table, you are prompted to insert any column:
When a user changes the table structure in SQL Server 2008 Enterprise Manager, you must delete the original table and re-create the new table to complete the changes to the table, and if you force the change, you will receive the following prompt: Save changes are not allowed. Your changes require that the following tables be deleted and recreated. You made changes to the label that could not be recreated or enabled the "Prevent saving changes that require the table to be recreated" option.

If you want to remove this hint, open SQL 2008 on the top
Tool-〉 Option-〉 a designer (designers)-〉 the Table Designer and Database Designer-> prevent saving changes that require recreating the table (right) hook away, no reboot 2008 is required.