My friend had this problem with movies on his set up. I went into nview and I changed his video overlay settings to "display fullscreen on secondary device". So now whenever he watches a movie it displays full screen on his TV.
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Athlon64 +3200, GeForceFX 5900, 1024 MB DDR 400, nForce3 250Gb chipset
80 GB SATA Seagate , 80 GB 7200 RPM Seagate, 120 GB 7200 Seagate
Lite-on SOHD-167T and Pioneer DVR-A06D
Running XP Professional and SuSe 9.1