PayPal payments "canceled"

-- url of the page with the problem -- : www.errorhead.com
-- HikaShop version -- : 2.5.0
-- Joomla version -- : 3.4.1
-- PHP version -- : 5.5.26

Hello, lately our HikaShop no longer handles PayPal payments correctly. All latest orders with PayPay checkout trigger the following behaviour:

1) An automated email is sent from the website to the admin with this content

TOPIC "Paypal Zahlungsbenachrichtigung abgewiesen:wrong receiver" (translate to: Paypal Payment notification dimissed:)

CONTENT "The money was sent to the wrong PayPal account, likely due to the customer trying to cheat... "(followed by a System link to the order in question)

2) The order is set to "canceled" in HikaShop (see attached screenshot - i manually set it to "confirmed" later)

ALL payments for those orders were recieved by Paypal though, and since so far all of them are virtual goods those Clients are a Little bit confused to say the least that once we received their Money we automatically set their orders to canceled before they were even able to download the files :-/

any idea what's going on? fyi i just recently updated hikashop to v2.5.0 because i was hoping to fix (and probably have) another Problem i encountered with "mixed" orders of virtual AND physical goods, probably caused by shipping issues ...

best regards