us english xbox 360 us english vista beta 2 broken medi

I have a US NTSC Xbox 360 and a US English copy of Vista Beta 2. When I try to use my 360 as a media center extender, Vista will error out after it tries to connect to my 360. My 360 stays on the black screen where it keeps trying to connect to the Media Center.
All this happens after I enter the 8-digit code on the PC, during the "configuration" phase of Media Center where it tries to upload the user settings to the extender. I've tried it with and without uploading the user settings and it does the same thing every time.