Windows 7: TCP/UDP checksum offloading

hello,

i have a voip application. i tested it on Windows 7.

when i see the RTP packets with Wireshark, i see that every UDP packet originating from the Windows 7 machine has UDP checksum error, and Wireshark suggests that it might be caused of 'UDP checksum offload'.



i received a bad/broken voice quality, i've tested in xp and it runs well.

what i want to ask are.

is TCP/UDP checksum offloading is enabled by default in Windows 7?
is there any other way to enable/disable this feature than setting it in the Registry?

or is this has something to do with the network interface driver? since i read that TCP/UDP checksum offloading let the network interface card to do the TCP/UDP checksum calculation, so that the packets will have a correct TCP/UDP checksum when they're sent on the wire. if that's right, i think that i shouldn't experience a bad/broken voice quality on the other side.


Thank you.