I get an operate error in system blade using a normal user.

I have XboxMediaCenter CVS build of July 25th 2006 compiled by T3CH and MC360 Beta 0.98657.
I delete all old version before installing this.
I activate Master Lock with a password.
I create new user with another password.
In MasterMode I have all accessible and in user mode i disable the System Blade.

It works all except:
when log with User and go to system blade, it asks me to insert the mastercode.
if I insert it correctly it's ok but if I mistake it, a message tell me that I have another 2 possibility and than
It blocks all and remaning on an empty system blade, no options and no button works excpet for right menu with system option.
At this point I must restart or log off user

I hope of to have been useful

OK I'm not speak English very well and it's possible that I haven't explained well
but the problem persist also in newer version 0.98691

a User with system blade limitation cannot mistake mastercode password when approaches to it
otherwise freeze all

thank for your attention