guest account & language hot keys

New computer
Installed vista ultimate 64 bit
enabled guest account with a password

when guest logs in he's unable to switch a language.
I've discovered that the language hot key is set to none
and can't be assigned.

I'm talking about control panel -> 'clock, language and region' -> 'change
keyboards or other input methods' -> 'change keyboards' under the 'keyboards
and languages' tab -> advanced key settings

'hot keys for input languages'
action:
'between input languages'
under the guest account when assigning the default or any other key and
clicking apply the the setting is resets to none

giving the guest account user or administrator privilages doesn't effect the
problem
creating a new account works fine as it is without any settings changes.

can anyone check or verify the problem?