I am having a problem with 2.4 on a user site (i.e. development url is http://ip-number/~username/).
Steps to recreate:
1) edit a page in cms
2) save and publish
3) click "Published Site" in cms to view the page
4) back in the cms, try to update a page. save and publish just spins, and I am asked to login again.
I am unable to edit and a javascript alert comes up saying "please login and then try again".
If I don't view the site by clicking on the "Published Site" link, I can make changes, save them, and view in a separate window in the browser.