One of these is an error message that pops up when a user tries to change a table via management studio design view by changing/deleting a column or adding a new column in the middle of the table. Instead of saving the change, the user gets the following error:
This may fool you or the user into believing there is a permissions issue preventing the table being updated, but it's actually a setting in SSMS - presumably to prevent the application hanging if the table involved was of any significant size.
The fix though is to simply uncheck box in the Options window.
Select "Tools" from the SSMS menu bar, then "Options..." from the drop down list.
Expand the "Designers" section, and under the "Table and Database Designers" section, you should find the "Prevent saving changes that require table re-creation" option, which you can disable.
Or you could just learn how to use ALTER TABLE statements in T-SQL!