An error occurred that requires the BizTalk service to terminate. General network error.

Error message: [DBNETLIB][ConnectionWrite (send()).]General network error. Check your network documentation.

Error source:

BizTalk host name: aaaaaProcessHost

Windows service name: aaaaaaProcessHost

This turned out to be a VMWare driver issue. Check out this article:

Large packet loss at the guest OS level on the VMXNET3 vNIC in ESXi 5.x / 4.x (2039495)