This Apple Care article should be saved for reference, as it is likely to recur.
If renaming a file you may get a message that said either “You don’t have sufficient access” or “You don’t have appropriate access privileges.” This may mean you tried to repair this situation by make a change to the Sharing and Permissions listings in the Finder’s Info window for a folder, and then select the “Apply to enclosed items” option from the Info window’s Action pop-up menu. You’re especially likely to see these symptoms if you do this for the Home directory itself. Here is the solution for a problem, an unannounced feature of Leopard.