schuon - 4:23 pm on Sep 7, 2011 (gmt 0)
martinacastro, do you have access to any SEO suite such as sistrix? With that you could check the distribution of your keywords. Here you'd pretty clearly see a -50 penalty. It that's the case you'll have to submit a reconsideration request.
If you PM me your domain, I can take a look at it (I hope that's ok with the forum policies)