Might get rid of my subwoofer!

[PCFan]

I was watching Bonnie and Clyde yesterday. In the scene where Clyde robs the bank and Bonnie is waiting in the car for him with the engine running, I could here a hum coming out of my subwoofer in the scene when Clyde was inside the bank which I suppose is the sound of the engine running from the car waiting outside. It felt like the bass was out of place and it didn't blend in well. I though that my subwoofer was malfunctioning for a second. I had my crossover set to 100hz on my receiver. My speakers only go down to 90hz. I tested the movie on my PC with my PC speakers and only if I turn the volume of my subwoofer almost all the way up I can here that same hum coming from the subwoofer. I might get rid of my subwoofer and satellite speakers and find a way to make room for my Polk M30 speakers because I can hear bass being directed from my subwoofer and it doesn't sound like it belongs in the movie. Also sometimes mens voices sound unnaturally deep and I'm not sure if it's because my satellite speakers have poor midrange and the subwoofer is playing some part in those voices if I set my crossover to 100hz. If I use my Polk bookshelf speakers, I won't have room for a subwoofer. So am I better off not using satellite speakers with subwoofer and just using bookshelf speakers without a subwoofer?