Hello, I have had this problem on a couple of machines running Windows 7 64bit. It appears to have something to do with the NIC-drivers. When you adjust some of the "Advanced properties" of the driver, the problem disappers with no side effects ( for as far as I have noticed ). At least, after the adjustments, I have had no complaints from customers. 1: Disable the "Large Send Offload". 2: Disable the "IPv4-checksum-offload". 3: Disable the "TCP-checksum-offload". 4: Disable the "UDP-checksum-offload". for IPv4 and IPv6 All NICs were Realtek models. I don't know of this has anything to do with it. I hope this information helps you to solve the problem cause I really think it's a great program otherwise!!!