i also have a lexus is 200. when i bought the car (52 plate) i had the same problem. I took it to the Lexus garage who told me that there was a recall on them and an exteded warrenty, mine was up 2 weeks previous but luckley the changed it for me. i would go to a lexus dealer and get them to look at it or take it somewhere who can maybe fix it.
Chris
August 2009