WordPress MU

On a relatively regular basis, a user makes some manipulation on a blog. Any subsequent request results in the blog not responding. Ever. The apache process hangs, uses 99% CPU, and nothing's to be done until apache is just restarted, or the process manually killed.
So far the only ultimate solution is to just disable the blog. I suspect it has to do with categories because a user for whom it happenned recently mentionned supressing categories.

Now I'm using a nightly from april, which i know is bad, but I was waiting for 1.0 to migrate. I'm gonna do that but it's gonna take a while, and I'd love to be able to correct this first, so i just thought i'd give a shot at asking the developpers if they recall correcting such a bug...

I have found the origin of the problem by doing an SQL export one of the blogs having problems.
There was a category in there, which parent ID was set to its own ID.
I'm not sure what sequence of events the user did to achieve that, but it's not the first time, so at least in the version I currently use it is possible.

Somewhere since then (I think) I know they did something to categories.

I've looked into the global categories plugin and couldn't find anything very different from my version and the latest release. I've looked through all categories code and I'm a bit puzzled ebcause I couldn't find a peace of code which would result in those 2 IDs being the same...

It's not just a WPMU bug, I find the same thing happening on my own server running two wordpress sites. Here's how I fixed it:
http://ocaoimh.ie/2006/10/01/killing-off-php/

hehe, love the cron task to kill hanging processes :-p.

However in my case I'm now *sure* it comes from the category having its own ID as the parent ID. I've spotted it on multiple blogs that made processes hang, and updating the category parent ID to 0 solves the problem instantly. It's probably a different problem from yours though, since in my case once the bug appears on a given blog, it's never ever possible to reload this blog without fixing the category (if i kill the process and reload the blog, process hangs again).

If you update this bug should disappear, we had the same problem on wordpress.com and added code in the last few months to handle it.

do you remember where / how the problem was fixed (global categories / regular cateories script / somewhere else ) ?
I'm gonna update, but it's gonna take some time since i want to migrate to multi server first, and I'm having this problem on an almost daily basis.