Error at checkout

-- url of the page with the problem -- : www.vestlisfiske.se
-- HikaShop version -- : 2.3.4
-- Joomla version -- : 3.3.6
-- PHP version -- : 5.3.29
-- Browser(s) name and version -- : Google Chrome Version 39.0.2171.71 m
-- Error-message(debug-mod must be tuned on) -- : Notice: Trying to get property of non-object in /home/vestlis/vestlisfiske.se/html/administrator/components/com_hikashop/helpers/helper.php on line 433

Hi,
I have upgraded to Joomla 3.3.6 from 2.5.27 10 days ago.
Now recently a strange error has occured. When trying to register as a new customer after placing products in the cart and clicking the submit button this error occur:

Notice: Trying to get property of non-object in /home/vestlis/vestlisfiske.se/html/administrator/components/com_hikashop/helpers/helper.php on line 433

If you try to login as an alreday registere customer that doesn't work either.Samer error message.
I tried to reinstall HikaShop Business and that worked but when the next customer places an order and the error occurs again.
What is wrong, is there any solution, please, the shop is on air and it is high season for winter fishing so it is necessary that it works.
Thanks.
Micke

Hi,
But I don't have any "error reporting" turned on. It is turned off.
The problem is that you can't place an order, this error message pops up and nothing else happens.
The strange thing is that the new customer gets signed in to the system but the order is not placed.
I have tried to compare this shop with an equal shop I have als owith HikaShop Business and the same setup except from the company name. Nothing differs except from that the other shop is working.
Now I tried everything today again, and after some erasing of users both under HikaShop and the main Joomla users, it seems to work again. Even though I haven't done anything else that these actions to delete some demo-users.
It feels very unstable in this installation and that error message is something I have never seen before...
Let's hop it won't happen again but til then I keep this topic open.

Hi,

I think that Nicolas wanted to say that you have to change the error reporting level, reduce it.
Regarding the error, could you give us the exact line in the indicated file ?