I'll just copy/paste something I wrote a while back that is relevant to your question:

It is a clash of cultures. And the muslims culture/traditions is interfering to much with are own. For instance There are many schools in are capital where there are more muslim children then native (Norwegian). The Norwegian children are being bullied because they are Norwegian, in Norway! Many schools have muslim related problems, such as the muslim girls and boys are refusing to have swimming educations together (and btw, non-western children are overrepresented in drowning related deaths here). One school even canceled their long annual Christmas traditions because of all the pressure from muslim parents. It has become a problem many places that the majority in "child-school" don't even speak Norwegian or understand it good enough, and teachers are unable to educate them.

Young ethnic Norwegians often come in trouble in the parts of the capital with large numbers of muslims, the Norwegians are being harassed (both psychically and verbally) because they are Norwegians and not muslims. Hell, we are even starting to get are first ghetto-like areas in Norway because all the ethnic Norwegians are moving away from the areas with large muslim populations because of the problems I have listed above and many others.

I have no problem living side my side by immigrants as long as they adapt to are way of life. But when are cultures are worlds apart and they refuse to adapt then they are not welcome here.

It is also worth mentioning that non-western immigrants are vastly overrepresented in rape statistics, it cumulated in the years 2006-2008 where 100% of all reported rapes in the capital was committed by non-western immigrants. And non-western (along with east-European) immigrants is vastly overrepresented in the general crime-statistics. And they are leaching on our welfare-systems, on average the Norway treasury lose about 480k$ in each non-western immigrant.