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.

>>213
They do have the right to refuse access to people. As global rule #14 states:
Remember: The use of 4chan is a privilege, not a right. The 4chan staff reserves the right to revoke access and remove content without notice.
http://www.4chan.org/rules#global