Saving changes is not permitted in SQL 2008 Management Studio

I am working on one of my project and i need to change the table design for change requirement, i done the changes and tried to save the table but SQL server throws an error message as described below:

"Saving changes is not permitted. The changes you have made require the following table 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."

How to solve this issue?

1. Go to Tools > Options it will open the Options dialog.
2. Select the Designers from left pane
3. Un check the Prevent saving changes that require table re-creation
4. Press OK button.

This will allow you to save the table changes.

Possible causes for this error:

1. You tried to change the data type of any column and the table already have some data exists.
2. You tried to add constraint to any column like Primary key which already have data exists.

thanks and regards.