*L* I have my MSIE set to xx-klingon (try using it on google *LOL*), but that also results in EN-US.
In fact, since that "language" does not exist at all, it should use [EN], but even using [EN] gets changed to [EN-US].
sidki3003 -- could be, I can't see any JS in the code tho. And deactivating JS also results in lang detection. Are you absolutely sure no language ID is transmitted?
BTW, if you use Opera, you can alter your User ID by using a custom.lng file: download a version for your Opera language from http://www.opera.com/download/modules.html (using an older version is no prob really, since nothing new has been added to the GUI since 6.02), and add these strings to it under the [Translation] header:
; <user agents>
20097="Mozilla/%s (Win32; U) Opera/6.03 [en]"
30000="Opera/6.03 (Win32; U) [en]"
The 20097 line controls all the Mozilla entries, so do not replace %s. You can alter just about anything else.
I haven't found the MSIE string yet alas.