So, a few months ago I, along with many others, had the pictos-won't-spread problem. Cue much sadness and frustration trying to connect only to end up with either a sad empty forest or a half-connected, laggy, clone-infested forest.
Anyway:
I fixed it. (this might not work for everyone, but for me, it worked 100%. It also worked for Sight when she tried it, so I'm not alone)
Basically, I connected to TEF through a VPN with a proxy server. A VPN is a Virtual Private Network, and is used to, among other things, connect to private networks (for example companies) and go on the internet anonymously.
http://en.wikipedia.org/wiki/Virtual_private_network
http://en.wikipedia.org/wiki/Proxy_server
This meant that my IP address changed, and somehow that made it work (magic??). Setting up a VPN might be tricky; I'm lucky and have a super tech-savvy sibling who did it for me.
Here's some nice and easy to read basics and I'm sorry I can't explain this any better:
http://www.pcworld.com/article/223044/vpns_for_beginners_to_experts.html
My very vague theory is that it has to do with your IP address somehow (no idea how that explains that my issues disappeared a few weeks later).