I am helping a friend of mine operate a multisite-wordpress install. The main address is http://blogs4me.de, and there are about a dozen sites in it. Since about a week ago (as far as we noticed), all of our blogs stopped working. That is, their frontpages still show headers and menus (the contents of header.php, as I was able to verify looking at the HTML source), but nothing more. The admin pages of all blogs were also unavailable. Trying to visit them in the browser just timed out. Also, the FTP server was unavailable. My friend has a root server running a Windows and WAMP setup.
My friend rebootet the server, and also uploaded the last known good WordPress version, 3.2 that is, because we thought it might have been a faulty bugfix upgrade. Now, at least, we can access the FTP server again, as well as the admin pages of all blogs of the network.
"Of course" (sigh!) he doesn't have a decent backup, and therefore we have to go forward and try to fix the situation from here.
It looks like the index.php or page.php scripts start executing. At least they execute the header.php, which is always first. The output from header.php is also sent to the browser. But then, all processing stops and no more output gets sent to the browser.
We also deactivated all plugins, and the no-content-behavior wasn't resolved.
Does anybody have a clue about what might trigger such behavior?
Is the PHP interpreter faulty?
Can a virus or script infection cause something like this? (I don't think so, because a) a virus scan of the whole Windows box didn't show anything unusual, and b) uploading WP 3.2 files should have fixed any maybe manipulated files)
Did we miss an important update?
Did we do one update too many?
Any help that might point us in the right direction is greatly appreciated. Thanks in advance.