We have seen this error primarily on customers using Powerhosting & Magento.
The full error says:
(WSDL) SOAP-ERROR: Parsing WSDL: Couldn't load from
'https://accountname/api/v2_soap?wsdl=1' : failed to load external
The error occurs because the shop does not respond fast enough for the integration. This can be fixed by raising the time value of your PHP default_socket_timeout to eg 15 seconds instead of 3 seconds.