We are experiencing the same problem. After clicking on “write a page” or “write a post” on the dashboard, the post text entry area has two tabs: “Visual” and “HTML”. “Visual” is selected. “HTML” can be clicked on, but now nothing happens when you do so.
This is after upgrading from 2.6.4 to 2.6.5.
Plugins are:
Statpress 1.2.9.2
Popularity contest 1.2.1
Akismet 2.2.2
The problem occurs in both IE 7 and firefox 3.
