I do recommend reading through that thread suggested earlier, but I doubt that the drain is blocked. My car actually leaves a series of water drips as I pull up my driveway (spaced very closely together), so I am pretty certain that the drain is clear. My car gets the smell when I shut off the A/C compressor (but leave the fan blowing), and then turn the A/C compressor back on at a later time.

I think this seems to be a common occurrence with these cars.