AdSense account disabled ! Why ?

I received this msg :

Quote:

While going through our records recently, we found that your AdSense
account has posed a significant risk to our AdWords advertisers. Since
keeping your account in our publisher network may financially damage
our advertisers in the future, we’ve decided to disable your account.

Why it is so ?
I have followed all FAQ rules, and not cheated !

Original post by SpeR