My issue has been solved. After installing 3 versions of wordpress and still having the same problem contacted the host. Turned out to be a mod_security restriction set by the hosting company. They removed the restriction and all is grand.
The rule that caused the problem was:
The rule “!(^$|^application/x-www-form-urlencoded$|^multipart/form-data)” is added under mod_security to prevent server from web attacks such as iframe injection or XSS attack(HTML/Javascript injection)
I’m having similar issues on a fresh install of 2.3.2. Can’t add catagories, either on the write post or manage/catagories. When I try and click add another page is displayed within the area where you enter the catagory name and info. Being a clean install and not an upgrade suggests this is a major bug. At the moment I am considering installing 2.3.1 untill this is figured out. Unless someone has an answer.
