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.

>>617
I bet if the spammers were from a first world country they wouldn't be banning an entire ISP.

Well, yeah, the information regarding ISP blocks explicitly states that "A number of international ISPs are disallowed from posting".