[AquaClic]

Okay, i figured this one out

It actually was an empty string missing in the x-currency.sql in the sql folder. I didn't try this because Virtual stated in a post before that it didn't work.

BEWARE
I'm posting this only to find out what the problem is. The problem is following and i'm still working on it, maybe someone can help me out:

I installed the module and it's working correctly on 4.1.10 but i get the error 2 posts above if i try to reinstall/uninstall the module.

I don't know what will happen with other 4.1.10 installations and i'm not sure if it is good for anyone to install it this way untill we've found a proper solution(!).

This is how my x-currency.sql in the sql folder looks like:

INSERT INTO xcart_config VALUES ('default_currency', 'Select default currency', 'EUR', 'Multi_Currency', 10, 'text', 'EUR','','');

INSERT INTO xcart_modules (module_name, module_descr, active) VALUES ('Multi_Currency','This module adds a multi currency support.','Y');

CREATE TABLE xcart_currency_rate (
    code CHAR( 3 ) NOT NULL DEFAULT '',
    rate DECIMAL( 12, 5 ) NOT NULL DEFAULT '1.00000',
    active CHAR( 1 ) NOT NULL DEFAULT 'N',
    order_by INT( 11 ) NOT NULL DEFAULT '0',
    PRIMARY KEY  (code)
) TYPE=MyISAM;

INSERT INTO xcart_currency_rate (code) SELECT code FROM xcart_currencies;

UPDATE xcart_currency_rate SET active = 'Y' WHERE code = (SELECT value FROM xcart_config WHERE name = 'currency_symbol') OR code = (SELECT xcart_currencies.code FROM xcart_currencies INNER JOIN xcart_config ON xcart_currencies.symbol = xcart_config.value AND xcart_config.name = 'currency_symbol');

CREATE TABLE xcart_customer_currency (
    login VARCHAR ( 32 ) NOT NULL DEFAULT '',
    currency CHAR( 3 ) NOT NULL DEFAULT '',
    PRIMARY KEY  (login)
) TYPE=MyISAM;

I only added an empty string in the first line.

If you want to try it for yourself then please backup everything you can and don't chop off my head if something goes wrong, i never told that this is a nice solution, it' merely an unfinished fix