Every time I try to play a DVD on my PC using Windows Media Player I get an error message saying it can't play DVD. WMP suggests that I change my video resloution. I haven't tried this because I don't want to have to do this every time I play a DVD. The DVD's play fine on a DVD player attached to my TV.

I have Vista Business. Any suggestions? Are there any free DVD players out there that are safe and free of adware, etc.

Thanks