Just opened section "Support", and entered "installation error 500" in search form input field, pressed "Go" button.
After recieving search results list, tryed to follow link. Any link is leading to page, that contains following text:
Internal Server Error
The server encountered an internal error or misconfiguration and was unable to complete your request.
Please contact the server administrator, firstname.lastname@example.org 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.
URL for example : http://wordpress.org/support/topic.php?id=29536