It doesn't sound silly to me because it's never happened to me. It sounds silly to me because I'm a rational adult living in the 21st century. Believing that ghosts must be responsible when your bed starts shaking or you hear whispers in the night is really no different than believing your city was flooded because you failed to sacrifice a goat to your gods this month. Just because you don't know what the reasonable explanation for something is, doesn't mean there isn't one.
i believe - ive heard too many stories from people who are credible as far as im concerned. i think that ghost hunters show is b.s. though. my grandpa was in the airforce and in the 50's they lived in a 300 year old house in england - my mom, her 3 brothers and sisters and both my grandparents always talked about how that house was haunted. all of them experienced various unexplainable things - hearing screaming and moaning, seeing things move and levitate on their own, beds shaking while they were sleeping in them. all 6 of them experienced this stuff.
discovery channel is showing an "a haunting" marathon. each episode is 1 hour true story of paranormal activity at different locales - usually a house w/ a family - the show is a mix of interviews w/ real life people and scary-in-their-own right reenactments. even if you dont believe in ghosts, its a pretty good show if you want to get creeped out.