Intelligent keys are coming with lots of new models of cars. Many times they make life a little easier, but the smart keys for some new Nissan Altimas have had just the opposite effect. The I-key can become permanently disabled if you leave it touching certain kinds of cell phones and the phone rings. There is no way to fix it, and these I-keys cost about $400 a pop. Nissan is including I-key malfunctions under the factory warranty, so call your dealer if you have been affected by this problem. A modified I-key -- which should be available by early fall -- is on the way from Nissan. In the meantime, the company advises that cell phones and I-keys should be kept at least one inch apart at all times. Owners of the 2007 Nissan Altima sedan and the 2007 Infiniti G35 have reported the most problems with I-key issues.