I recently updated to Windows 8 and get alot of invalid packet transfers. It says "Ip checksum offload?" (Wireshark) and most of my packets get lost. The checksum is 0x00. I also updated my NIC drivers, but this did not help. My internet worked well in Windows 7 with no problems at all. Some websites do not work and some do. And when I open multiple tabs, they won't work at all: just one tab / website will load. Looks like the packet get timeout.
Both UDP and TCP are affected.