I am working on translating an SharePoint 2010 website and one of the things that is driving me crazy is finding a way to translate IE dialog messages. Does anybody already had this problem? Please check the screenshot below.
I am using SharePoint 2010, with Language Packs installed (Japanese and Spanish). Testing with Internet Explorer 9. My system language is set to en-US.

Update #1:
- Using Google Chrome the same messages were displayed correctly (in Japanese).
- After installing system Japanese language packs and IE language pack the problem persisted
This problem keeps unsolved :(