Tonight all of a sudden I noticed from the Extender, when trying to connect to the Vista PC, the step 'Starting Up' would stay on the screen a long time, until the TV screen after a minute or so would just go blank and to get any response back from the Extender, I would have to either pop in a DVD (it is the Linksys DMA2200, I don't believe the Extender is at fault here, for once, though), or shut off the power, turn it back on and try again, from the home screen to connect to Vista. They have been, until the last few days, been set up and communicating just fine with good results in general.
I have a PC in my living room with Vista Home Premium SP2 64 bit and a Media Center Extender in the family room.