I have a Sharp 42XD1E 1080p capable LCD TV and a laptop that outputs up tp 1920x1200 via DVI. I can connect the laptop over DVI to HDMI and get the desktop display at 1080p perfectly.

When I try to play a 1080i HDTV TS file from the laptop using either Videolan or powerdvd 7 the TV will automatically go to full screen while the video player on the laptop display will stay in its windowed mode with some of the desktop still visible. The main problem is the LCD TV shows the video output from the laptop change from 1080p to 1280x720 (720p) as soon as the TS file starts to playback. The TS file is definitely 1080i and the original display from the laptop is definitely 1080p. Why would this change happen, everything else stays at 1080p, games etc.