You were probably blocked because of variant Creutzfeldt–Jakob disease (AKA human bovine spongiform encephalopathy AKA human mad cow disease).
The US recently removed the block for this on:
• people who were stationed with the military or lived on a base in Europe from 1980-1996, and
• people who lived in Europe for five years or more from 1980 to the present, except for two exceptions. Those are people who lived in Ireland or France for 5 years or more cumulatively from 1980-2001, and people who lived in the UK for 3 months or more cumulatively from 1980-1996.
Canada, New Zealand, Poland, Finland and the Czech Republic have similar rules, according to Wikipedia.