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 
entity "https://accountname/api/v2_soap?wsdl=1"

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.