1997 Nissan Altima Non-Working Key and Cruise Control

I have a 1997 Nissan Altima with automatic locks. The locks operate perfectly from the inside, both with the automatic lock button as well as with the manual levers. However, the key will not turn in the lock on the driver's side. I have tried three different keys, and all three work in both the trunk and ignition. All Nissan literature says that that vehicle has only one key and that it is all-purpose. At first I thought that the lock was frozen, but it spent the day in a heated garage and no change. Any ideas? Also, the cruise control won't work. I checked all fuses and all are okay. Any idea where I should start on that one? I love your site and would appreciate any insights you might have for me. Thank you!