This sounds like the same problem that there has been for 2 days in July (see posts above).
I get after a long time:
Internal Server Error
The server encountered an internal error or misconfiguration and was unable to complete your request.
Please contact the server administrator, email@example.com
and inform them of the time the error occurred, and anything you might have done that may have caused the error.
More information about this error may be available in the server error log.
Additionally, a 500 Internal Server Error error was encountered while trying to use an ErrorDocument to handle the request.
Wiki is down since this morning!
Same behavior as above, or:
Your request has reached a system that is acting as a gateway or proxy to fulfill the request made by you.
This system is currently experiencing a temporary error reaching the web site you are requesting.
Your website (if you host with us) is safe and sound. Our engineers are already aware of this issue and should have it fixed in a couple of minutes. Thanks for your patience in the meantime!