range fan hood leaking

We have had quite a bad winter this year, and for the first time my range fan hood is leaking. Anyone had this problem before, and what did you do to fix it? This is the second time this year it's leaked, both times after a cold spell.

The water is leaking onto the stove, and we're catching it in a pan, so I doubt it's too dangerous (we're not using the fan, of course). Our house is 9 years old, and we've never had the problem before.

Anyone had any experience with this?

Thanks so much!