Look in your postgresql.conf file for LC_MESSAGES.
LC_MESSAGES is a locale-related variable, so that users can see diagnostic messages in their language/dialect. 'en_UK' would stand for "UK English". Since you can probably understand American English without too much trouble (

), you might want to just comment out any lines which specify "en_UK", but be careful, because some of them might be needed by your application.
See this thread in the PostgreSQL mail lists:
http://archives.postgresql.org/pgsql...6/msg01212.php
According to this, it looks like those variables can be different on different operating systems, so you might need to do some research, if you need LC_MONETARY, or LC_NUMERIC, etc...