During the Mountain Lion installation I have selected the English language as the system language. However, the dialog asking for my password – that appears when you need to install an application, or when you want to unlock a preference pane – is in Dutch. I'm currently in The Netherlands, but I don't see how this might be related to the language of one type of dialog.
Here below an image of the dialog. As you can see there's even a mix of Dutch and English:
I haven't been to other countries yet with this MacBook Pro, so don't know if it's actually dependent on location.
How can I fix this issue?