Someone in my studio designed a webpage some years ago, and now the client decided to change the server (he moved to a Linux Apache server running Gen2 SMP, 64 bits, PHP version 5.3.8, Standard MYSQL version 5). It suddenly started to do weird things.

When clicking on a link that requires login, the page redirects you to the login page using header() function in PHP. Curiously, the page shows this:

OK

The server encountered an internal error or misconfiguration and was unable to complete your request. Please contact the server administrator, [no address given] 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. HTTP/1.1 200 OK Date: Mon, 15 Oct 2012 17:27:32 GMT Server: Apache/2.2.22 (Unix) FrontPage/5.0.2.2635 X-Powered-By: PHP/5.3.8 Expires: Thu, 19 Nov 1981 08:52:00 GMT Cache-Control: no-store, no-cache, must-revalidate, post-check=0, pre-check=0 Pragma: no-cache Keep-Alive: timeout=5, max=399 Connection: Keep-Alive Transfer-Encoding: chunked Content-Type: text/html 232c

Then the page itself, and then, another header:

0 1f4

OK

The server encountered an internal error or misconfiguration and was unable to complete your request. Please contact the server administrator, [no address given] 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. 0

What's most intriguing is that if you refresh the page or hit enter on the url, it loads correctly. I've been checking the logs, and it only blames of an inexisting favicon. I also checked the .htaccess, everything was correct (RewriteBase was / as intended, and the only stuff there is another rule that moves ^en/ requests to request?lang=en. Has anyone faced something like this?

Edit: IE doesn't trigger these two headers. This is getting wierder.