"404 – not found" when updating posts

Jan – thanx for leaving off the last part ?? I thank you even more fore trying to help:
phpinfo gives back lots of information, but I’m not quite sure what to look for? as far as I can see, there’s no mod_security module, at least with that name..

well, well… my wordpress site needed some good night sleep, apparently..
everything works just fine today; eastern character encoding, permalinks.. Everything I’ve been struggling yesterday and last night. Go figure!
What I would like to know now is – what the hell happened? I’m really pleased things are back to normal, but I’m terrified with the idea of going through all this once again, especially when I can’t be sure that it will end up the same way. So I would really like to find out if it was the server side error, application bug, database failure or something else..

That’s totally bizarre. If you’ve not changed anything then you may want to ask your hosting provider to see if anything was changed.

The good thing is that it’s all working again… but without any idea why it happened it could occur again…

hmm.. friend of mine has a joomla site running with the same ISP and had some issues as well. according to him, provider claims that everything is running smooth and no new features, scripts or anything else has been deployed.
is Bizzaro still around? any news there?

UPDATE:
same thing occured on my another blog!! everything seemed to work well – but as soon as I’ve edited post title with croatian letters – boom!
“Not Acceptable
An appropriate representation of the requested resource /test/wp-admin/post.php could not be found on this server.
Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request.”
what’s going on?!?
i’m still on 3.0.1 on that one.. and best for the end; now it works just fine.. now i’m totally confused.

From using The Google(tm) it really seems like a mod_security issue…

Give this a try. Using a blog that has the problem make a backup copy of your blog’s .htaccess file (cp .htaccess .htaccess-save-my-life) and add the following lines

<IfModule mod_security.c>
   # Turn off mod_security filtering.
   SecFilterEngine Off

   # The below probably isn't needed, but better safe than sorry.
   SecFilterScanPOST Off
</IfModule>

If that causes your blog to go insane just restore the old .htaccess file.

If after that step you can’t get the “Not acceptable” to return, then try removing the lines and see if it comes back. The purpose of this test is just to see if this is it.

If this fixes it then talk to your host about relaxing those rules.

If it does NOT fix it, let us know here.

Good luck.