I completely concur with all said by Awar. The root of the problem is the existance of different ethnic groups in the same space. But it goes deeper than that, centuries of bickering between europeans have also created historical "hates" between brethren folk (for example, a large portion of Portuguese "hate" the "castillians" which makes neither sense nor is good for our cultural relations).
I think that set quotas are the answer, excluding non-europeans from Europe effectively. I also think that european cooperation can only be for the common good and I see no "evil" in inner-european immigration, if within specific numbers.
For example, the number of Eastern Europeans (from Romania, Ukraine, Kosovo) currently living in Portugal is simply scary. It's neigh impossible to pass by a building under construction without seeing eastern europeans working there, to an extent where "working as a kosovar" means working as a slave for peanuts....
Though I have to admit some Ukrainian and Russian chicks are HOT!
