jbayabas - Number one is the most common -- 90% of the time. I'm sure the OP did not receive an email because he was already directed to Invalid Activity support page when logging in.
I am actually directed to "AdSense account may be disabled for policy reasons" which without any further advice is useless. We run around 15 different sites using Adsense (or we did) and they are very different in terms of design and layout.
I have not had an email from Google Adsense. Even if I made the changes (whatever they are) I have no way of contacting the Adsense team.
Just in case anyone has not seen the page we are directed to, here it is