I haven't seen this one myself, but have you tried deleting the contents of, and then re-uploading, wp-admin and wp-includes? That's what I'd do, just to make sure there's nothing left over from 2.3.

--- Mr. DOS

That happened to me and I tried what mister dos said and that's one of the reasons my blog is gone. I have it combined with my portfolio site now. Which is ok since I am working on a wordpress theme for it.

Agree with Mr. Dos, whenever I've had trouble with WP after an install it's always been the admin folder. Reuploading has fixed it. If the trouble happens when you're posting, it does sound like an wp-admin problem. They also often suggest on the WP site to change to the default theme to see if things work with that, then you can narrow it down. Maybe you;ve done that already; I know you're an experienced wp person.

So last night I bit the bullet and did a clean install of wordpress 2.5, still with no luck. Just for kicks and giggles, I set up a new 2.5 database and pointed my blog towards that and everything works fine! So that issue lies with the database somewhere. I thought of just transferring my database via SQL dumping, but my query is too large (15mb) and it's making the server choke. On top of that I find it curious that the table structures between my new install and old database are different.

Wordpress is keeping their mouth closed tight on this too. I haven't heard anything back from them and I can see by the posts on their forum that I am not the only person having these problems.

So I'm still trying to find an answer for this as time permits, but for now I'm dead in the water.