Changing Language in Regional Settings

I'm running WinXP Pro SP2.

Once I change the "Standards and Options" under the Regional Options tab in
Regional and Language Options then hit Apply and OK the change doesn't apply.

I reopen the Regional and Language Options and the language is set back to
what it was before I tried to change it.

This is odd because I have no trouble changing to a language I've never used
before, but if I try to change back to English (US) the settings will not
stay after I hit Apply and OK.

I could temporarily switch to English (Aus) but once I switched to another
language English (Aus) and English (US), along with other language settings
I've used before, will not be applied once I hit Apply and OK!

Is there any way to forcibly change the language settings using the registry
or some fix for this problem?

Thanks for any help!