ISP blocked due to abuse?

Well, it seems today that I'm now unable to post anything over at the 4chan imageboards, otherwise I get this message:
"Posting from your ISP has been blocked due to abuse. [More Info]"
I can still browse the site, all the images and threads load fine, I just can't post. What gives? I've never posted spam or porn.

I guess that at least I should be glad for discovering I'm not the only Venezuelan lurking 4chan. I tried posting with Tor but it gives me an error (not banned, just a server error or something)

Just two questions guys: Your IP starts with 190 or 201? And did any of you get a response from admin@4chan.org?

I bet if the spammers were from a first world country they wouldn't be banning an entire ISP.