If you use one of http://www.bodum.com/pages/products/productshow.asp?vFamID=1 these, be sure you’ve put the carafe in the holder before you add the coffee grounds.
Also, if you happen to occasionally alternate between coffee and tea, I strongly recommend you do not accidently put lemon in your morning coffee.
Yes, these are both things I have done in the past week or so.
Reminds me of this old “Fox Trot” comic strip…