I'm having this problem, preventing me from logging in to Appropedia:
"Immediately logging outhttp://en.wikipedia.org/wiki/Help:Logging_in#Immediately_logging_out
Some ISPs use transparent proxieshttp://en.wikipedia.org/wiki/Transparent_proxywhich cause problems logging in. If you find that you are automatically logged out just after you have logged in, and removing all your Wikipedia cookies does not fix the issue, try using the secure serverhttps://secure.wikimedia.org/wikipedia/en/wiki/Main_Page(much slower) to bypass the proxy. This happens most often with some satellite ISPs (particularly HughesNethttp://en.wikipedia.org/wiki/HughesNet /DirecWay http://en.wikipedia.org/wiki/DirecWay/DirecPChttp://en.wikipedia.org/wiki/DirecPC )."
The problem is that this is not a Wikimedia site, so that secure server link does not help. It's important, as I'm one of the Appropedia admins and have admin tasks I need to do, while I'm staying in a location (Lago Atitlan, Guatemala) where the ISP uses a satellite connection.
I'm not sure why, but it affects some MediaWiki sites and not others. I stay logged in to Wikipedia, Greenlivingpedia http://www.greenlivingpedia.org/and the OLPC wiki http://wiki.laptop.org, but not to Appropediahttp://www.appropedia.org/or Envirowiki http://en.envirowiki.info, where I get logged out on the first . I can stay logged in to the Creative Commons wiki for several clicks before getting logged out, and with some extra effort I successfully made an edit there.