I too am having this issue.  I have a case open:  3031073 I run Win7 Media Center for TV watching and recording.  When I connect XBox360 to Media Center it takes forever to accept inputs from remote if it ever does.  nine times out of 10 it disconnects......because the PC has locked.  Hard reset is required.  When running any video or sound on PC, it lags tremendously and sound stutters. I removed MWB and it all stopped.  Everything was working as it was supposed to.  I have since rein