Okay, so I've got the mini-DVI to HDMI plugged into a 22" HDTV from my iMac. When I turn on the external preview in Vegas, it works, but it keeps going black and resetting itself. Very annoying. I've checked all the plugs and cables, and even tried different ones. Then I tried using a SD TV via mini-DVI to RCA. Same thing. Any ideas? Thanks.