Google Webmaster Tools is reporting crawl errors for links that never existed, and if i check the "Linked from" tab for a given error link, it shows another that never existed.
They all mention joomla/ which is not the cms used on this domain (it's wordpress fyi).
Exampled: http://example.com/joomla/index.php/component/user/register
Linked from: http://example.com/joomla/component/user/login?return=L2######
What is going on?
UPDATE 1
I tried something: I provided one of the faulty urls to the "Fetch as Google" functionality. Instead of returning a 404, it returns a 301 to another Joomla page.
HTTP/1.1 301 Moved Permanently
Server: Apache/2.4.3
X-Powered-By: PHP/5.4.4-10
X-Pingback: http://example.com/xmlrpc.php
Expires: Wed, 11 Jan 1984 05:00:00 GMT
Cache-Control: no-cache, must-revalidate, max-age=0
Pragma: no-cache
Set-Cookie: PHPSESSID=1fgr5v2oip39miibuptd51s8h0; path=/
Set-Cookie: woocommerce_items_in_cart=0; expires=Sat, 12-Jan-2013 11:44:01 GMT; path=/
Location: http://example.com/joomla/component/user/register
Content-Type: text/html; charset=iso-8859-1
Content-Length: 387
Date: Sat, 12 Jan 2013 12:44:01 GMT
Via: 1.1 varnish
Connection: keep-alive
Accept-Ranges: bytes
Age: 0
<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN">
<html><head>
<title>301 Moved Permanently</title>
</head><body>
<h1>Moved Permanently</h1>
<p>The document has moved <a href="http://example.com/joomla/component/user/register">here</a>.</p>
<p>Additionally, a 301 Moved Permanently
error was encountered while trying to use an ErrorDocument to handle the request.</p>
</body></html>
