Originally Posted by sov211

Replace your battery unless you are CERTAIN that it is less than 3 years old and that it is FULLY charged and holding that full charge. Do nothing else to the car until you verify the battery condition and do not be fooled by the fact that "the engine starts every time". Low battery voltage in the XK ( and many modern cars) causes random system symptoms including but not limited to warning lights, door, window, seat problems, frozen or slow touch screen action, convertible roof and window issues...and in virtually every case the cause is low battery voltage.
Once you have a new battery, purchase a CTEK battery maintainer and use it whenever the car is not in use. You will eliminate the possibility of the failures named above and like the rest of us who use the maintainer, you will have a completely problem -free XK ( because you have the 4.2 litre version). These are amazingly reliable cars - amazing because something this beautiful is not usually also reliable. The XK is.
Is anyone else here getting tired of repeating the battery mantra?