Out of ideas, helps if you can.

[Skipachu]

Right click My Computer and select "Manage". Click Device Manager -> Network adapters. Then right-click your NIC and choose Properties. When the properties window opens, select the Advanced tab. In the left pane will be the options to edit. Select each of the Offload settings (Large Send Offload, TCP Offload, etc) and set the value to False or Disabled. My NIC has two version of each of these, one for IPv4 and one for IPv6; i turned them both off in each case.