“Post=0” and cannot post problems after database move

I’m running a WordPress 2.5 blog and have just moved from a server that ran MySQL 5 to one that runs MySQL4. I exported the database in PHPMyAdmin using the MySQL 4.0 compatibility function.

I set up the installation on the new server and everything seemed to work OK – all my old posts were still there.

I tried creating a new post, hit publish – and it didn’t appear.

I found it had been moved into ‘drafts’. I cannot now edit the post – if I click on the title it sends me back to the posts folder. If I hover over the post I can see from the link it has been set as “post=0” whereas other posts in the drafts folder (created before the server move) have a number other than zero.

When I try to create further new posts now they do not even appear in the drafts folder when I click publish – they just disappear.

Any idea what has gone wrong here and how I can fix it?