When I play a movie in itunes from my laptop to my TV, it won't play on the TV (but is fine on the laptop)

Ok, I have a weird question here. I am connecting my Dell Laptop to my Sony TV (40", 1080p) with an HDMI cable. When I play a movie in iTunes, it plays fine on the laptop, but if I move it to the Sony TV, it will not play. . I've tried it different ways: movies play on my laptop fine when disconnected from the TV. They even play fine on the laptop, when the screen is extended between the laptop and TV. When it moves to the TV, it stops playing. Does anyone know what the problem is? I purchased the TV in early 2008, so it's not the newest. But last week, I connected it to a Toshiba and it worked fine.

Oh, and one other point, right now, I don't have internet (this question is coming from my phone's hotspot), so could that make a difference? Why would it?

Thanks to anyone who can help.

-Tim