If in fact you find a water leak as other members have suggested, look at this technical service bulletin (found in the TSB list). It is very helpful in diagnosing water leaks. Pressurizing cabin as they tell you how to do was very helpful to me.
TSB 07-14-6 "Water Leak-Front Floor Area"
It is very important to take the time to find out exactly where water may be entering the car's interior. Just guessing is a waste of more time.
My water leak was from side window weatherstrip retainer. Read my thread about how I resolved my problem if yours, through diagnosis is the same. Other water leaks can be from having windshield replaced (poorly done), or leaks through the firewall area due to missing rubber plugs or missing factory sealing in weld areas of firewall metal pieces.
Last edited by s197gt; 03-13-2010 at 03:21 PM.
Reason: add more information