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.

>That fucking feel when you've been banned for like 2 months, still naively saving reaction images and the like in the vain hope that you'll soon be unbanned, and moot has basically just confirmed that you'll never post again
>That fucking feel when you use Ubuntu so you can't even try Hotspot Shield