portal logon page only in English

Hi Experts,

We copied prod ep to one of test boxes and we now face following problem there.

Logon page is always displayed in English - no matter what lang is set in the browser.

Guest user has no language specified in UME, however even if I set it to German for instance, logon screen remains in Eng.

Any help will be apreciated and rewarded with points.

Thanks,

Artur