I had quite anoing issue with WordPress. It started around version 2.0, but not sure about. I came across these problems on multiple installations and hosting providers. Basicly I got two problems:

1) After saving a post/page my post.php displayed blank screen. It was not blocking issue, but quite anoing.

2) Second problem was duplicating of drafts after saving. Draft was saved in 6 copies of itself!

Both these issues combined make me little bit crazy,  but I got a lot of other things to solve. I did some dirty hacks to work around it, but I finally had time to search for some ultime solution. It took me only couple of minutes and I found a thread about same problems. If you do not want to read all comments for other symptoms, just take a look at my last comment.