Hi,
Your log tells it all:
173.0.82.126 - - [06/Dec/2012:16:38:18 +0200] "POST /index.php?option=com_hikashop&ctrl=checkout&task=notify¬if_payment=paypal&tmpl=component&lang=he&Itemid=349 HTTP/1.0" 303 - "-" "-"
The notification of paypal is redirected. And if you look at the next line you can see :
173.0.82.126 - - [06/Dec/2012:16:38:19 +0200] "GET /index.php/he/2012-11-05-11-51-10?view=login HTTP/1.0" 200 17660 "-" "-"
Which means that it is redirected to the login page.
So apparently, your website shop menu is only accessible to logged in users or something like that. So when PayPal tries to notify it, Joomla tells it that it has to login first and thus the notification doesn't reach hikashop and the order is not confirmed.