Check out problem

I have this error when checking out from shopping:

Notice: unserialize() [function.unserialize]: Error at offset 4622 of 4914 bytes in /home/kemmnest/public_html/shp/library/cart/order.php on line 56

Warning: Cannot modify header information - headers already sent by (output started at /home/kemmnest/public_html/shp/library/cart/order.php:56) in /home/kemmnest/public_html/shp/library/environment/response.php on line 23

Please help me solve it!

THX!

What version of OpenCart?
What shipping method?
What payment method?
What mods have you installed?
What template changes have you made?
Can you reproduce it more than once?
Do you have a link we can see?

The error is due to trying to load the order out of the order_data (temp) table during payment. But unless there was some problem entering that order into the table, it shouldn't really have a problem.

Hi!
It's  OpenCart V0.7.9 , at  http://kemmnestat.ru/shp/
After installation it works properly, but after I added the hungarian language pack,
and set the demo product informations for hungarian at the admin sight, it's just cant
check out.
But if I skip the langugae back to english, I can check out the order.
After that, if I check back for my order history, in english, it appears, but in hungarian not.
You may register at a random name, and try to order, to see what happens.
It must be a setting problem or just simply the hungarian language pack is not comlete?
The pack is from the open cart contributions :
http://www.opencart.com/index.php?route ... tion_id=42

Hungarian pack was made for 0.7.7. This is 0.7.9 so it is probably
A) incomplete
and
B) has a charset encoding problem.

You might need to start fresh. Follow the FAQ here

Thanks for Your help!