I don't think that the majority of the europeans hates the americans, but it is true that there are some important groups who don´t like them, specially in the Left and some urban literate people.
The reason why this happens is because of the influence the United States have in the world these days, and that puts them in the center of atention. After the cold war, and with the present globalization process, the United States have an influence that reaches every corner of the world. It is the price to pay. For example, I wouldn't give a damn if the american foreign policy makes some mistakes, but because this is a globalized world where the US are the dominant world power, that must concern everyone. In fact, even the internal affairs in the US affects the rest of the world, and because of that, every american action is watched closely.
As for Europe vs. United States, or more exactly, the way we look at each other, the problem is in the diferences that we have and that have grown in the last 50 years. In my personal case, for example, everytime I watch american politicians ending thir speeches with "God bless America", I get annoyed, because in european politics God is dead, and I can´t understand how it isn't possible for an atheist person to become the US president. And we could continue with death penalty, environmental issues, the fact that we play football (soccer) and you don't, and the fact that americans are allways proclaiming their country as the land of freedom in a way that almost sounds like a religious dogma, when in europe there are countries with a constitution even more democratic than the american one.
Another thing is the ignorance that sometimes americans show about the rest of the world. I have a friend who went to visit The United States and a mayor of some town asked him "Is there democracy in Europe?" and another guy said "I love riding my bike, how can I go travel to Europe by bike?" These would be a joke if it wasn't for the fact that this is the most powerfull country in the world. And what worries us is that this often happens with people with high responsabilities and high education. I mean, people look at this and ask "How can they elect a president that does not have any knowledge about the world around?" or "How can this guys produce TV shows that are completely abject, where the sex for the sex is the only issue, and then when we look at it we see clouds in every breasts, something that I see wherever I look at any beach here?". Acording to a recent survey 40% of the americans can't point their country in a world map and we say "This is too dangerous. How is it possible that this country is the dominant power, when the majority of the congressmen don't have a passport and never travelled abroad?"
Surely this is not true for every american, but the fact that this happens in a country like USA, then people stay very suspicious about the americans intentions. Finally, the majority of the europeans gets their information about United States in films and TV shows, and most of them are either futile or presenting a very naive and manicheistic (don't know the spelling) view about the rest of the world.
So, in my opinion, the problem is that we are different and everyone seems to expect the other side to behave just like our own.