2.1.2 – post.php errors after upgrading. Help needed.

I upgraded to 2.1.2 last night, following the codex directions carefully (deactivating plugins, making backups etc). The site looked OK afterwards once all the plugins were reactivated. (www.sokwanele.com/thisiszimbabwe)

However:

I am unable to post properly in the admin side.

Problem 1
I write a post, and when I try to save it or publish it I get a dialogue box that says something like

you’re trying to open post.php, do you want to save, use realpayer etc

It does not, as usual, reload after saving with a preview.

I discovered that although I wasn’t being given preview, when I pressed publish, it WAS publishing to my site. As a result I ended up with three duplicate posts because I kept trying to get it to work.

Problem 2

‘Manage posts’ in the admin side, will not allow me to delete any of the duplicate entries. If I press delete, the post appears to delete, but when I refresh the page its right back there. None are taken off the front page.

We managed to resolve the duplicate entries by deleting them directly from the database, but we obviously cannot work like this.

How can we fix this as quickly as possible – its an active site and large audience and we need to post every day, sometimes more than once.

Should we put the old admin file back?