Another "login" problem

So it used to be magical before; I click “sign in with steam”, I type in my login and password, and it works out.
Now whenever I just click “sign in with steam”, I instantly get


Content Encoding Error (content_encoding_error)

Server response could not be decoded using encoding type returned by server.
This is typically caused by a Web Site presenting a content encoding header of one type, and then encoding the data differently. 

Plus that’s not only in the steam sign in link(garrysmod.org/user/, that also happens in garrysmod.org. So I’m limited to only use Toybox, which isn’t that “Woo awesome” since I’m trying to get some tools, playermodels…etc.
I tried using IE 8 instead of Firefox (3.8/5 not beta) but that didn’t work out, so is it some maintenance in the website or am I experience an unusual problem?
Much appreciated.