MinGW g++ gives warnings in the wrong language (German instead of English)

My problem is the following:
When I compile a C++ Project with eclipse (Juno, 64bit, Java 7u3) on my Windows 7 laptop, I get german errors/warnings. This results in warnings showing as errors in eclipse.

Windows 7, 64bit, settings :

Display Language: English
Format: German (Switzerland)
Location: Switzerland
Language for non-Unicode programs: English (Canada)

On my other Windows 7 (64bit) computer, I have the exact same settings and don't have any problems.

I tried:

• Adding -Duser.language=en to the end of my eclipse.ini file.
  Which did not work.
• Changing the Format to English.
  Which actually worked but is not really an option due to the wrong format in other places.
• Many different things I can't remember (e.g. Environment variables in eclipse, etc.)
  Again, nothing helped.

I finally solved it :D
I just added a new environment varibale. I still have no clue why it works on one computer (as on that one I have not set this variable) but at least it finally works on my laptop as well and is (I think) a good (the correct?) solution:

Control Panel -> System -> Advanced System Settings -> Environment Varibales... -> System variables -> New.. -> Variable: LC_ALL, Value: en_US.UTF-8

Now I have english warnings/errors when I compile and eclipse behaves as it should.