WordPress MU

Hi,
i've been using wpmu for a time now to explore its possibilities. Right now i have one problem i cannot resolve myself:

When i change some settings in "Site Options" of my wpmu i cannot change them back to the original settings.
Example: Activating "WP Backend Menus" plugins is possible, but its impossible to change it back to disabled. The checkbox stays checked.
The same thing happens when i try to deactivate the "upload media button" of pictures.

phperror.log don't log, apache error.log too.

I am using apache 2.2.8, php 5.2.5, mysql 5.0.51a.

Its possible for me to disable the plugins backend menu in the mysql database, but i don't think thats the right way.

If someone can help, i would be very happy!

I'm thinking maybe a plugin is interfering.

Thanks for your response andrea_r, is this functioning in your 2.8.2 install?

I disabled the memcache object cache, wp super cache and activated the default theme. No plugins. Everything is working o.k. EXCEPT:

Site Admin < Options < WP Backend Menus < Plugins uncheck
And
Site Admin < Options < Upload Media Button < Images uncheck

No problems with previous mu installs, only the 2.8.2. Logs are silent, including mod_security 1.9.4.

Edit: I can change the options directly in the mysql database in the table wp-sitemeta < menu_items and change a:1:{s:7:"plugins";s:1:"1";} to a:1:{s:7:"plugins";s:1:"0";}
But i prefer to stay away from editing the database myself.

long time listener, first time caller.. nah really, I know what I'm doing and
I'm having a duplicate error disabling plugin menus from the back end.
no plugins, MU 2.8.2, Apache 2.2.8, PHP 5.2.5, mySQL 5.0.5 - seen two related post for users with similar issue in 2.8.2?... checking the trac