Publishing/saving a post with formatting/images redirects to home page

[conanh]

On some servers (seems to be consistent across the same server), when a user creates a post with any formatting (e.g. bold, color, an image, etc.), publishing or saving as a draft does not save the post but instead redirects from the post.php page to the root page.

This is basically what it looks like: ​http://www.screencast.com/t/WRut2fpoGa

I have three installs on the same server, each going to a different subdomain. Two of the installs are brand new with no plugins. All have the same problem, so my assumption is that the issue is likely related to an Apache or PHP setting.

Also, my install worked fine several weeks ago, then suddenly didn't. This seems to support the above hypothesis.

The problem exists in 2.7+, including the 2.8 beta 2.

[conanh]

Related support forum posts:
​http://wordpress.org/support/topic/274071
​http://wordpress.org/support/topic/273483
​http://wordpress.org/support/topic/273623
​http://wordpress.org/support/topic/273675
​http://wordpress.org/support/topic/273763
​http://wordpress.org/support/topic/272445
​http://wordpress.org/support/topic/270010

[Denis-de-Bernardy]

need... steps... to reproduce. :-(

[ryan]

Closing pending more information. Perhaps mod_security?